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140-472: Meteorology is a branch of the atmospheric sciences (which include atmospheric chemistry and physics) with a major focus on weather forecasting . The study of meteorology dates back millennia , though significant progress in meteorology did not begin until the 18th century. The 19th century saw modest progress in the field after weather observation networks were formed across broad regions. Prior attempts at prediction of weather depended on historical data. It

280-645: A GPS clock for data logging . Upper air data are of crucial importance for weather forecasting. The most widely used technique is launches of radiosondes . Supplementing the radiosondes a network of aircraft collection is organized by the World Meteorological Organization . Remote sensing , as used in meteorology, is the concept of collecting data from remote weather events and subsequently producing weather information. The common types of remote sensing are Radar , Lidar , and satellites (or photogrammetry ). Each collects data about

420-613: A Problem in Mechanics and Physics that it should be possible to forecast weather from calculations based upon natural laws . It was not until later in the 20th century that advances in the understanding of atmospheric physics led to the foundation of modern numerical weather prediction . In 1922, Lewis Fry Richardson published "Weather Prediction By Numerical Process," after finding notes and derivations he worked on as an ambulance driver in World War I. He described how small terms in

560-496: A Roman geographer, formalized the climatic zone system. In 63–64 AD, Seneca wrote Naturales quaestiones . It was a compilation and synthesis of ancient Greek theories. However, theology was of foremost importance to Seneca, and he believed that phenomena such as lightning were tied to fate. The second book(chapter) of Pliny 's Natural History covers meteorology. He states that more than twenty ancient Greek authors studied meteorology. He did not make any personal contributions, and

700-433: A Turkish officer, Selim Bimbashi, were made between 1839 and 1842, and two got to the point about 30 kilometres (20 miles) beyond the present port of Juba , where the country rises and rapids make navigation very difficult. Lake Victoria was first sighted by Europeans in 1858 when British explorer John Hanning Speke reached its southern shore while traveling with Richard Francis Burton to explore central Africa and locate

840-767: A distance of 20 days' journey till it reaches the nearest Ethiopians." Modern exploration of the Nile basin began with the conquest of the northern and central Sudan by the Ottoman viceroy of Egypt, Muhammad Ali , and his sons from 1821 onward. As a result of this, the Blue Nile was known as far as its exit from the Ethiopian foothills and the White Nile as far as the mouth of the Sobat River. Three expeditions under

980-468: A factor of 15 at Aswan. Peak flows of over 8,212 m /s (290,000 cu ft/s) occurred during late August and early September, and minimum flows of about 552 m /s (19,500 cu ft/s) occurred during late April and early May. The Bahr al Ghazal and the Sobat River are the two most important tributaries of the White Nile in terms of discharge. The Bahr al Ghazal's drainage basin

1120-463: A farmer's potential harvest. In 1450, Leone Battista Alberti developed a swinging-plate anemometer , and was known as the first anemometer . In 1607, Galileo Galilei constructed a thermoscope . In 1611, Johannes Kepler wrote the first scientific treatise on snow crystals: "Strena Seu de Nive Sexangula (A New Year's Gift of Hexagonal Snow)." In 1643, Evangelista Torricelli invented the mercury barometer . In 1662, Sir Christopher Wren invented

1260-460: A few weeks, climatology studies the frequency and trends of those systems. It studies the periodicity of weather events over years to millennia, as well as changes in long-term average weather patterns, in relation to atmospheric conditions. Climatologists , those who practice climatology, study both the nature of climates – local, regional or global – and the natural or human-induced factors that cause climates to change. Climatology considers

1400-482: A gale was expected. FitzRoy coined the term "weather forecast" and tried to separate scientific approaches from prophetic ones. Over the next 50 years, many countries established national meteorological services. The India Meteorological Department (1875) was established to follow tropical cyclone and monsoon . The Finnish Meteorological Central Office (1881) was formed from part of Magnetic Observatory of Helsinki University . Japan's Tokyo Meteorological Observatory,

1540-629: A group of meteorologists in Norway led by Vilhelm Bjerknes developed the Norwegian cyclone model that explains the generation, intensification and ultimate decay (the life cycle) of mid-latitude cyclones , and introduced the idea of fronts , that is, sharply defined boundaries between air masses . The group included Carl-Gustaf Rossby (who was the first to explain the large scale atmospheric flow in terms of fluid dynamics ), Tor Bergeron (who first determined how rain forms) and Jacob Bjerknes . In

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1680-521: A legitimate branch of physics. In the 18th century, the invention of the thermometer and barometer allowed for more accurate measurements of temperature and pressure, leading to a better understanding of atmospheric processes. This century also saw the birth of the first meteorological society, the Societas Meteorologica Palatina in 1780. In the 19th century, advances in technology such as the telegraph and photography led to

1820-705: A limited sense to describe the section between Lake No and Khartoum. At Khartoum, the river is joined by the Blue Nile . The White Nile starts in equatorial East Africa, and the Blue Nile begins in Ethiopia. Both branches are on the western flanks of the East African Rift . The source of the Blue Nile is Lake Tana in the Gish Abay region in the Ethiopian Highlands . The source of

1960-596: A peak flow of over 680 m /s (24,000 cu ft/s) in October. During the dry season (January to June) the White Nile contributes between 70% and 90% of the total discharge from the Nile. Below Renk , the White Nile enters Sudan, it flows north to Khartoum and meets the Blue Nile. The course of the Nile in Sudan is distinctive. It flows over six groups of cataracts , from the sixth at Sabaloka just north of Khartoum northward to Abu Hamad . The tectonic uplift of

2100-495: A period up to a year. His system was based on dividing the year by the setting and the rising of the Pleiad, halves into solstices and equinoxes, and the continuity of the weather for those periods. He also divided months into the new moon, fourth day, eighth day and full moon, in likelihood of a change in the weather occurring. The day was divided into sunrise, mid-morning, noon, mid-afternoon and sunset, with corresponding divisions of

2240-525: A place described as the source of the Rukarara tributary, and by hacking a path up steep jungle-choked mountain slopes in the Nyungwe Forest found (in the dry season ) an appreciable incoming surface flow for many kilometres upstream, and found a new source, giving the Nile a length of 6,758 km (4,199 mi). The White Nile leaves Lake Victoria at Ripon Falls near Jinja, Uganda , as

2380-949: A snapshot of a variety of weather conditions at one single location and are usually at a weather station , a ship or a weather buoy . The measurements taken at a weather station can include any number of atmospheric observables. Usually, temperature, pressure , wind measurements, and humidity are the variables that are measured by a thermometer, barometer, anemometer, and hygrometer, respectively. Professional stations may also include air quality sensors ( carbon monoxide , carbon dioxide , methane , ozone , dust , and smoke ), ceilometer (cloud ceiling), falling precipitation sensor, flood sensor , lightning sensor , microphone ( explosions , sonic booms , thunder ), pyranometer / pyrheliometer / spectroradiometer (IR/Vis/UV photodiodes ), rain gauge / snow gauge , scintillation counter ( background radiation , fallout , radon ), seismometer ( earthquakes and tremors), transmissometer (visibility), and

2520-642: A trace of an atmosphere on the Moon . Planetary atmospheres are affected by the varying degrees of energy received from either the Sun or their interiors, leading to the formation of dynamic weather systems such as hurricanes (on Earth), planet-wide dust storms ( on Mars ), an Earth-sized anticyclone on Jupiter (called the Great Red Spot ), and holes in the atmosphere (on Neptune). At least one extrasolar planet, HD 189733 b , has been claimed to possess such

2660-537: A weather system, similar to the Great Red Spot but twice as large. Hot Jupiters have been shown to be losing their atmospheres into space due to stellar radiation, much like the tails of comets. These planets may have vast differences in temperature between their day and night sides which produce supersonic winds, although the day and night sides of HD 189733b appear to have very similar temperatures, indicating that planet's atmosphere effectively redistributes

2800-606: Is also responsible for twilight in Opticae thesaurus ; he estimated that twilight begins when the sun is 19 degrees below the horizon , and also used a geometric determination based on this to estimate the maximum possible height of the Earth's atmosphere as 52,000 passim (about 49 miles, or 79 km). Adelard of Bath was one of the early translators of the classics. He also discussed meteorological topics in his Quaestiones naturales . He thought dense air produced propulsion in

2940-465: Is an archaeological site located in alluvial deposits formed by an ancient channel of the Nile in the Affad region of southern Dongola Reach , Sudan. There are two theories about the age of the integrated Nile. One is that the integrated drainage of the Nile is of young age and that the Nile basin was formerly broken into series of separate basins, only the most northerly of which fed a river following

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3080-656: Is called an-Nīl . In Biblical Hebrew , it is הַיְאוֹר ‎, Ha-Ye'or or הַשִׁיחוֹר ‎, Ha-Shiḥor . The English name Nile and the Arabic names en-Nîl and an-Nîl both derive from the Latin Nilus and the Ancient Greek Νεῖλος . Beyond that, however, the etymology is disputed. Homer called the river Αἴγυπτος , Aiguptos , but in subsequent periods, Greek authors referred to its lower course as Neilos ; this term became generalized for

3220-625: Is increasingly connected with other areas of study such as climatology. The composition and chemistry of the atmosphere is of importance for several reasons, but primarily because of the interactions between the atmosphere and living organisms. The composition of the Earth's atmosphere has been changed by human activity and some of these changes are harmful to human health, crops and ecosystems. Examples of problems which have been addressed by atmospheric chemistry include acid rain, photochemical smog and global warming. Atmospheric chemistry seeks to understand

3360-696: Is known as the Bahr al Jabal ("Mountain River" ). Just south of the town is the confluence with the Achwa River . The Bahr al Ghazal , 716 kilometers (445 mi) long, joins the Bahr al Jabal at a small lagoon called Lake No , after which the Nile becomes known as the Bahr al Abyad , or the White Nile, from the whitish clay suspended in its waters. When the Nile floods it leaves a rich silty deposit which fertilizes

3500-578: Is longer and rises in the Great Lakes region. It begins at Lake Victoria and flows through Uganda and South Sudan. The Blue Nile begins at Lake Tana in Ethiopia and flows into Sudan from the southeast. The two rivers meet at the Sudanese capital of Khartoum . The northern section of the river flows north almost entirely through the Nubian Desert to Cairo and its large delta , and

3640-487: Is not mandatory to be hired by the media. Each science has its own unique sets of laboratory equipment. In the atmosphere, there are many things or qualities of the atmosphere that can be measured. Rain, which can be observed, or seen anywhere and anytime was one of the first atmospheric qualities measured historically. Also, two other accurately measured qualities are wind and humidity. Neither of these can be seen but can be felt. The devices to measure these three sprang up in

3780-469: Is now known as the hydrologic cycle . His work would remain an authority on meteorology for nearly 2,000 years. The book De Mundo (composed before 250 BC or between 350 and 200 BC) noted: After Aristotle, progress in meteorology stalled for a long time. Theophrastus compiled a book on weather forecasting, called the Book of Signs , as well as On Winds . He gave hundreds of signs for weather phenomena for

3920-516: Is restricted to the free atmosphere , the region above the planetary boundary layer . Early pioneers in the field include Léon Teisserenc de Bort and Richard Assmann . Atmospheric chemistry is a branch of atmospheric science in which the chemistry of the Earth's atmosphere and that of other planets is studied. It is a multidisciplinary field of research and draws on environmental chemistry, physics, meteorology, computer modeling, oceanography, geology and volcanology and other disciplines. Research

4060-525: Is slightly longer. Of the world's major rivers, the Nile is one of the smallest, as measured by annual flow in cubic metres of water. About 6,650 km (4,130 mi) long, its drainage basin covers eleven countries: the Democratic Republic of the Congo , Tanzania , Burundi , Rwanda , Uganda , Kenya , Ethiopia , Eritrea , South Sudan , Sudan , and Egypt . In particular, the Nile

4200-572: Is the largest of any of the Nile's sub-basins, measuring 520,000 square kilometers (200,000 sq mi) in size, but it contributes a relatively small amount of water, about 2 m /s (71 cu ft/s) annually, because tremendous volumes of water are lost in the Sudd wetlands. The Sobat River, which joins the Nile a short distance below Lake No, drains about half as much land, 225,000 km (86,900 sq mi), but contributes 412 cubic meters per second (14,500 cu ft/s) annually to

4340-485: Is the primary water source of Egypt, Sudan and South Sudan. The Nile is an important economic driver supporting agriculture and fishing. The Nile has two major tributaries : the White Nile and the Blue Nile . The White Nile is traditionally considered to be the headwaters stream. However, the Blue Nile is the source of most of the water of the Nile downstream, containing 80% of the water and silt . The White Nile

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4480-405: Is the scientific study of the upper atmosphere of the Earth — the atmospheric layers above the stratopause — and corresponding regions of the atmospheres of other planets, where the entire atmosphere may correspond to the Earth's upper atmosphere or a portion of it. A branch of both atmospheric chemistry and atmospheric physics, aeronomy contrasts with meteorology, which focuses on the layers of

4620-400: Is to explain the observed circulations on the basis of fundamental principles from physics . The objectives of such studies incorporate improving weather forecasting , developing methods for predicting seasonal and interannual climate fluctuations, and understanding the implications of human-induced perturbations (e.g., increased carbon dioxide concentrations or depletion of the ozone layer) on

4760-451: The 22° and 46° halos . The ancient Greeks were the first to make theories about the weather. Many natural philosophers studied the weather. However, as meteorological instruments did not exist, the inquiry was largely qualitative, and could only be judged by more general theoretical speculations. Herodotus states that Thales predicted the solar eclipse of 585 BC. He studied Babylonian equinox tables. According to Seneca, he gave

4900-411: The Earth's magnetic field lines. In 1494, Christopher Columbus experienced a tropical cyclone, which led to the first written European account of a hurricane. In 1686, Edmund Halley presented a systematic study of the trade winds and monsoons and identified solar heating as the cause of atmospheric motions. In 1735, an ideal explanation of global circulation through study of the trade winds

5040-642: The Kitab al-Nabat (Book of Plants), in which he deals with the application of meteorology to agriculture during the Arab Agricultural Revolution . He describes the meteorological character of the sky, the planets and constellations , the sun and moon , the lunar phases indicating seasons and rain, the anwa ( heavenly bodies of rain), and atmospheric phenomena such as winds, thunder, lightning, snow, floods, valleys, rivers, lakes. In 1021, Alhazen showed that atmospheric refraction

5180-607: The Murchison Falls until it reaches the northern shores of Lake Albert where it forms a significant river delta. Lake Albert is on the border of the Democratic Republic of the Congo, but the Nile is not a border river at this point. After leaving Lake Albert, the river continues north through Uganda and is known as the Albert Nile . The White Nile flows into South Sudan just south of Nimule , where it

5320-680: The Nubian Swell diverts the river south-west for over 300 km, following the structure of the Central African Shear Zone embracing the Bayuda Desert . At Al Dabbah it resumes its northward course towards the first cataract at Aswan forming the S-shaped Great Bend of the Nile mentioned by Eratosthenes . In the north of Sudan, the river enters Lake Nasser (known in Sudan as Lake Nubia),

5460-651: The Paleogene and Neogene Periods (66 million to 2.588 million years ago) a series of separate closed continental basins each occupied one of the major parts of the Sudanese Rift System: Mellut rift , White Nile rift , Blue Nile rift , Atbara rift and Sag El Naam rift . The Mellut Basin is nearly 12 kilometers (7.5 mi) deep at its central part. This rift is possibly still active, with reported tectonic activity in its northern and southern boundaries. The Sudd swamp which forms

5600-456: The Rhône and Po , one of the three Mediterranean rivers with the largest water discharge . The standard English names "White Nile" and "Blue Nile" refer to the river's source, derived from Arabic names formerly applied to only the Sudanese stretches that meet at Khartoum . In the ancient Egyptian language , the Nile is called Ḥꜥpy (Hapy) or Jtrw (Iteru), meaning "river". In Coptic ,

5740-626: The Smithsonian Institution began to establish an observation network across the United States under the leadership of Joseph Henry . Similar observation networks were established in Europe at this time. The Reverend William Clement Ley was key in understanding of cirrus clouds and early understandings of Jet Streams . Charles Kenneth Mackinnon Douglas , known as 'CKM' Douglas read Ley's papers after his death and carried on

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5880-471: The Sudd region. More than half of the Nile's water is lost in this swamp to evaporation and transpiration . The average flow rate of the White Nile at the tails of the swamps is about 510 m /s (18,000 cu ft/s). From here it meets with the Sobat River at Malakal . On an annual basis, the White Nile upstream of Malakal contributes about 15% of the total outflow of the Nile. The average flow of

6020-578: The atmospheric sciences . Meteorology and hydrology compose the interdisciplinary field of hydrometeorology . The interactions between Earth's atmosphere and its oceans are part of a coupled ocean-atmosphere system. Meteorology has application in many diverse fields such as the military, energy production, transport, agriculture, and construction. The word meteorology is from the Ancient Greek μετέωρος metéōros ( meteor ) and -λογία -logia ( -(o)logy ), meaning "the study of things high in

6160-417: The heat capacity of gases varies inversely with atomic weight . In 1824, Sadi Carnot analyzed the efficiency of steam engines using caloric theory; he developed the notion of a reversible process and, in postulating that no such thing exists in nature, laid the foundation for the second law of thermodynamics . In 1716, Edmund Halley suggested that aurorae are caused by "magnetic effluvia" moving along

6300-632: The phlogiston theory . In 1777, Antoine Lavoisier discovered oxygen and developed an explanation for combustion. In 1783, in Lavoisier's essay "Reflexions sur le phlogistique," he deprecates the phlogiston theory and proposes a caloric theory . In 1804, John Leslie observed that a matte black surface radiates heat more effectively than a polished surface, suggesting the importance of black-body radiation . In 1808, John Dalton defended caloric theory in A New System of Chemistry and described how it combines with matter, especially gases; he proposed that

6440-428: The "Victoria Nile." It flows north for some 130 kilometers (81 mi) to Lake Kyoga . The last part of the approximately 200 kilometers (120 mi) river section starts from the western shores of the lake and flows at first to the west until just south of Masindi Port , where the river turns north, then makes a great half circle to the east and north to Karuma Falls . For the remaining part, it flows westerly through

6580-570: The 20th and 21st centuries, with the advent of computer models and big data, meteorology has become increasingly dependent on numerical methods and computer simulations. This has greatly improved weather forecasting and climate predictions. Additionally, meteorology has expanded to include other areas such as air quality, atmospheric chemistry, and climatology. The advancement in observational, theoretical and computational technologies has enabled ever more accurate weather predictions and understanding of weather pattern and air pollution. In current time, with

6720-526: The Aristotelian method. The work of Theophrastus remained a dominant influence in weather forecasting for nearly 2,000 years. Meteorology continued to be studied and developed over the centuries, but it was not until the Renaissance in the 14th to 17th centuries that significant advancements were made in the field. Scientists such as Galileo and Descartes introduced new methods and ideas, leading to

6860-414: The Ethiopian rainy season when rainfall is especially high in the Ethiopian Highlands ; the rest of the year, the great rivers draining Ethiopia into the Nile have a weaker flow. In harsh and arid seasons and droughts, the Blue Nile dries out completely. The flow of the Blue Nile varies considerably over its yearly cycle and is the main contribution to the large natural variation of the Nile flow. During

7000-630: The Ethiopian Highlands, satellite imagery was used to identify dry watercourses in the desert to the west of the Nile. A canyon, now filled by surface drift, represents the Eonile that flowed during 23–5.3 million years before present. The Eonile transported clastic sediments to the Mediterranean; several natural gas fields have been discovered within these sediments. During the late- Miocene Messinian salinity crisis , when

7140-491: The Ethiopian Highlands. The Blue Nile flows about 1,400 kilometres to Khartoum, where the Blue Nile and White Nile join to form the Nile. Ninety percent of the water and ninety-six percent of the transported sediment carried by the Nile come from the Atbarah and Blue Nile, both of which originate in Ethiopia, with fifty-nine percent of the water coming from the Blue Nile. The erosion and transportation of silt only occurs during

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7280-518: The Great was the first to propose that each drop of falling rain had the form of a small sphere, and that this form meant that the rainbow was produced by light interacting with each raindrop. Roger Bacon was the first to calculate the angular size of the rainbow. He stated that a rainbow summit cannot appear higher than 42 degrees above the horizon. In the late 13th century and early 14th century, Kamāl al-Dīn al-Fārisī and Theodoric of Freiberg were

7420-482: The Mediterranean Sea was a closed basin and evaporated to the point of being empty or nearly so, the Nile cut its course down to the new base level until it was several hundred metres below world ocean level at Aswan and 2,400 m (7,900 ft) below Cairo. This created a very long and deep canyon which was filled with sediment after the Mediterranean was recreated. At some point the sediments raised

7560-581: The Middle East and Africa, and described being told of the source of the Nile in Abyssinia (Ethiopia). Later in the 15th and 16th centuries, travelers to Ethiopia visited Lake Tana and the source of the Blue Nile in the mountains south of the lake. Supposedly, Paolo Trevisani ( c.  1452 –1483), a Venetian traveller in Ethiopia, wrote a journal of his travels to the origin of the Nile that has since been lost. Although James Bruce claimed to be

7700-539: The Modification of Clouds , in which he assigns cloud types Latin names. In 1806, Francis Beaufort introduced his system for classifying wind speeds . Near the end of the 19th century the first cloud atlases were published, including the International Cloud Atlas , which has remained in print ever since. The April 1960 launch of the first successful weather satellite , TIROS-1 , marked

7840-464: The Nile carries little water (5% of that of the Congo River , for example). The Nile basin is complex, and because of this, the discharge at any given point along the main stem depends on many factors including weather, diversions, evaporation and evapotranspiration , and groundwater flow. Upstream from Khartoum (to the south), the river is known as the White Nile , a term also used in

7980-676: The Nile near the southern point of the Great Bend. The Nile has been the lifeline of civilization in Egypt since the Stone Age , with most of the population and all of the cities of Egypt developing along those parts of the Nile valley lying north of Aswan. However, the Nile used to run much more westerly through what is now Wadi Hamim and Wadi al Maqar in Libya and flow into the Gulf of Sidra . As

8120-526: The Nile since ancient times. A tune, Hymn to the Nile , was created and sung by the ancient Egyptian peoples about the flooding of the Nile River and all of the miracles it brought to Ancient Egyptian civilization. Water buffalo were introduced from Asia, and the Assyrians introduced camels in the 7th century BCE. These animals were raised for meat and were domesticated and used for ploughing—or in

8260-647: The Nile. When in flood the Sobat carries a large amount of sediment, adding greatly to the White Nile's color. The Yellow Nile is a former tributary that connected the Ouaddaï highlands of eastern Chad to the Nile River Valley c.  8000 to c.  1000 BCE . Its remains are known as the Wadi Howar . The wadi passes through Gharb Darfur near the northern border with Chad and meets up with

8400-554: The Sudd wetlands of South Sudan, the upper reaches of the White Nile remained largely unknown to the ancient Greeks and Romans. Vitruvius thought that source of the Nile was in Mauritania, on the "other" (south) side of the Atlas Mountains . Various expeditions failed to determine the river's source. Agatharchides records that in the time of Ptolemy II Philadelphus , a military expedition had penetrated far enough along

8540-545: The White Nile at Lake Kawaki Malakal, just below the Sobat River, is 924 m /s (32,600 cu ft/s); the peak flow is approximately 1,218 m /s (43,000 cu ft/s) in October and minimum flow is about 609 m /s (21,500 cu ft/s) in April. This fluctuation is caused by the substantial variation in the flow of the Sobat, which has a minimum flow of about 99 m /s (3,500 cu ft/s) in March and

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8680-836: The White Nile, even after centuries of exploration, remains in dispute. The most remote source that is indisputably a source for the White Nile is the Kagera River ; however, the Kagera has tributaries that are in contention for the farthest source of the White Nile. Two start in Burundi: the Ruvyironza River (also known as the Luvironza) and the Rurubu River . In addition, in 2010, an exploration party in Rwanda went to

8820-422: The advancement in weather forecasting and satellite technology, meteorology has become an integral part of everyday life, and is used for many purposes such as aviation, agriculture, and disaster management. In 1441, King Sejong 's son, Prince Munjong of Korea, invented the first standardized rain gauge . These were sent throughout the Joseon dynasty of Korea as an official tool to assess land taxes based upon

8960-444: The afterlife. The east was thought of as a place of birth and growth, and the west was considered the place of death, as the god Ra , the Sun, underwent birth, death, and resurrection each day as he crossed the sky. Thus, all tombs were west of the Nile, because the Egyptians believed that in order to enter the afterlife, they had to be buried on the side that symbolized death. As the Nile was such an important factor in Egyptian life,

9100-957: The air". Early attempts at predicting weather were often related to prophecy and divining , and were sometimes based on astrological ideas. Ancient religions believed meteorological phenomena to be under the control of the gods. The ability to predict rains and floods based on annual cycles was evidently used by humans at least from the time of agricultural settlement if not earlier. Early approaches to predicting weather were based on astrology and were practiced by priests. The Egyptians had rain-making rituals as early as 3500 BC. Ancient Indian Upanishads contain mentions of clouds and seasons . The Samaveda mentions sacrifices to be performed when certain phenomena were noticed. Varāhamihira 's classical work Brihatsamhita , written about 500 AD, provides evidence of weather observation. Cuneiform inscriptions on Babylonian tablets included associations between thunder and rain. The Chaldeans differentiated

9240-482: The ancient calendar was even based on the three cycles of the Nile. These seasons, each consisting of four months of thirty days each, were called Akhet , Peret , and Shemu . Akhet, which means inundation, was the time of the year when the Nile flooded, leaving several layers of fertile soil behind, aiding in agricultural growth. Peret was the growing season, and Shemu, the last season, was the harvest season when there were no rains. Owing to their failure to penetrate

9380-498: The appendix Les Meteores , he applied these principles to meteorology. He discussed terrestrial bodies and vapors which arise from them, proceeding to explain the formation of clouds from drops of water, and winds, clouds then dissolving into rain, hail and snow. He also discussed the effects of light on the rainbow. Descartes hypothesized that all bodies were composed of small particles of different shapes and interwovenness. All of his theories were based on this hypothesis. He explained

9520-420: The atmosphere below the stratopause. In atmospheric regions studied by aeronomers, chemical dissociation and ionization are important phenomena. All of the Solar System's planets have atmospheres. This is because their gravity is strong enough to keep gaseous particles close to the surface. Larger gas giants are massive enough to keep large amounts of the light gases hydrogen and helium close by, while

9660-412: The atmosphere can be divided into distinct areas that depend on both time and spatial scales. At one extreme of this scale is climatology. In the timescales of hours to days, meteorology separates into micro-, meso-, and synoptic scale meteorology. Respectively, the geospatial size of each of these three scales relates directly with the appropriate timescale. Other subclassifications are used to describe

9800-455: The atmosphere from a remote location and, usually, stores the data where the instrument is located. Radar and Lidar are not passive because both use EM radiation to illuminate a specific portion of the atmosphere. Weather satellites along with more general-purpose Earth-observing satellites circling the earth at various altitudes have become an indispensable tool for studying a wide range of phenomena from forest fires to El Niño . The study of

9940-615: The beginning of the age where weather information became available globally. In 1648, Blaise Pascal rediscovered that atmospheric pressure decreases with height, and deduced that there is a vacuum above the atmosphere. In 1738, Daniel Bernoulli published Hydrodynamics , initiating the Kinetic theory of gases and established the basic laws for the theory of gases. In 1761, Joseph Black discovered that ice absorbs heat without changing its temperature when melting. In 1772, Black's student Daniel Rutherford discovered nitrogen , which he called phlogisticated air , and together they developed

10080-460: The best known products of meteorologists for the public, weather presenters on radio and television are not necessarily professional meteorologists. They are most often reporters with little formal meteorological training, using unregulated titles such as weather specialist or weatherman . The American Meteorological Society and National Weather Association issue "Seals of Approval" to weather broadcasters who meet certain requirements but this

10220-400: The calculations led to unrealistic results. Though numerical analysis later found that this was due to numerical instability . Starting in the 1950s, numerical forecasts with computers became feasible. The first weather forecasts derived this way used barotropic (single-vertical-level) models, and could successfully predict the large-scale movement of midlatitude Rossby waves , that is,

10360-411: The camels' case, carriage. Water was vital to both people and livestock. The Nile was also a convenient and efficient means of transportation for people and goods. The Nile was also an important part of ancient Egyptian spiritual life. Hapi was the god of the annual floods, and both he and the pharaoh were thought to control the flooding. The Nile was considered to be a causeway from life to death and

10500-561: The causes of these problems, and by obtaining a theoretical understanding of them, allow possible solutions to be tested and the effects of changes in government policy evaluated. Atmospheric dynamics is the study of motion systems of meteorological importance, integrating observations at multiple locations and times and theories. Common topics studied include diverse phenomena such as thunderstorms , tornadoes , gravity waves , tropical cyclones , extratropical cyclones , jet streams , and global-scale circulations. The goal of dynamical studies

10640-479: The central part of the basin may still be subsiding. The White Nile Rift system, although shallower than the Bahr el Arab rift , is about 9 kilometers (5.6 mi) deep. Geophysical exploration of the Blue Nile Rift System estimated the depth of the sediments to be 5–9 kilometers (3.1–5.6 mi). These basins were not interconnected until their subsidence ceased, and the rate of sediment deposition

10780-443: The chaotic nature of the atmosphere. Mathematical models used to predict the long term weather of the Earth ( climate models ), have been developed that have a resolution today that are as coarse as the older weather prediction models. These climate models are used to investigate long-term climate shifts, such as what effects might be caused by human emission of greenhouse gases . Meteorologists are scientists who study and work in

10920-412: The church and princes. This was supported by scientists like Johannes Muller , Leonard Digges , and Johannes Kepler . However, there were skeptics. In the 14th century, Nicole Oresme believed that weather forecasting was possible, but that the rules for it were unknown at the time. Astrological influence in meteorology persisted until the eighteenth century. Gerolamo Cardano 's De Subilitate (1550)

11060-615: The climate with public health. During the Age of Enlightenment meteorology tried to rationalise traditional weather lore, including astrological meteorology. But there were also attempts to establish a theoretical understanding of weather phenomena. Edmond Halley and George Hadley tried to explain trade winds . They reasoned that the rising mass of heated equator air is replaced by an inflow of cooler air from high latitudes. A flow of warm air at high altitude from equator to poles in turn established an early picture of circulation. Frustration with

11200-422: The clouds and winds extended up to 111 miles, but Posidonius thought that they reached up to five miles, after which the air is clear, liquid and luminous. He closely followed Aristotle's theories. By the end of the second century BC, the center of science shifted from Athens to Alexandria , home to the ancient Library of Alexandria . In the 2nd century AD, Ptolemy 's Almagest dealt with meteorology, because it

11340-589: The confluence with the Blue Nile the only major tributary is the Atbarah River , also known as the Red Nile. Roughly halfway to the sea, it originates in Ethiopia north of Lake Tana , and is around 800 kilometers (500 mi) long. The Atbarah flows only while there is rain in Ethiopia and dries very rapidly. During the dry period of January to June, it typically dries up north of Khartoum . The Blue Nile ( Amharic : ዓባይ , ʿĀbay ) springs from Lake Tana in

11480-463: The course of the Blue Nile to determine that the summer floods were caused by heavy seasonal rainstorms in the Ethiopian Highlands, but no European of antiquity is known to have reached Lake Tana. The Tabula Rogeriana depicted the source as three lakes in 1154. Europeans began to learn about the origins of the Nile in the 14th century when the Pope sent monks as emissaries to Mongolia who passed India,

11620-452: The creation of weather observing networks and the ability to track storms. Additionally, scientists began to use mathematical models to make predictions about the weather. The 20th century saw the development of radar and satellite technology, which greatly improved the ability to observe and track weather systems. In addition, meteorologists and atmospheric scientists started to create the first weather forecasts and temperature predictions. In

11760-624: The design and construction of instruments for studying the atmosphere and the interpretation of the data they provide, including remote sensing instruments. In the United Kingdom, atmospheric studies are underpinned by the Meteorological Office. Divisions of the U.S. National Oceanic and Atmospheric Administration (NOAA) oversee research projects and weather modeling involving atmospheric physics. The U.S. National Astronomy and Ionosphere Center also carries out studies of

11900-492: The development of Egyptian civilization. Because the river overflowed its banks annually and deposited new layers of silt, the surrounding land was very fertile. The Ancient Egyptians cultivated and traded wheat, flax , papyrus and other crops around the Nile. Wheat was a crucial crop in the famine-plagued Middle East. This trading system secured Egypt's diplomatic relationships with other countries and contributed to economic stability. Far-reaching trade has been carried on along

12040-402: The dry season the natural discharge of the Blue Nile can be as low as 113 m /s (4,000 cu ft/s), although upstream dams regulate the flow of the river. During the wet season, the peak flow of the Blue Nile often exceeds 5,663 m /s (200,000 cu ft/s) in late August (a difference of a factor of 50). Before the placement of dams on the river the yearly discharge varied by

12180-585: The early study of weather systems. Nineteenth century researchers in meteorology were drawn from military or medical backgrounds, rather than trained as dedicated scientists. In 1854, the United Kingdom government appointed Robert FitzRoy to the new office of Meteorological Statist to the Board of Trade with the task of gathering weather observations at sea. FitzRoy's office became the United Kingdom Meteorological Office in 1854,

12320-605: The entire river system. Thus, the name may derive from Ancient Egyptian expression n ꜣ r ꜣ w-ḥ ꜣ w(t) (lit. 'the mouths of the front parts'), which referred specifically to the branches of the Nile transversing the Delta, and would have been pronounced ni-lo-he in the area around Memphis in the 8th century BCE. Hesiod at his Theogony refers to Nilus (Νεῖλος) as one of the Potamoi (river gods), son of Oceanus and Tethys . Another derivation of Nile might be related to

12460-485: The existence of a circulation cell in the mid-latitudes, and the air within deflected by the Coriolis force resulting in the prevailing westerly winds. Late in the 19th century, the motion of air masses along isobars was understood to be the result of the large-scale interaction of the pressure gradient force and the deflecting force. By 1912, this deflecting force was named the Coriolis effect. Just after World War I,

12600-420: The explanation that the cause of the Nile 's annual floods was due to northerly winds hindering its descent by the sea. Anaximander and Anaximenes thought that thunder and lightning was caused by air smashing against the cloud, thus kindling the flame. Early meteorological theories generally considered that there was a fire-like substance in the atmosphere. Anaximander defined wind as a flowing of air, but this

12740-440: The field of meteorology. The American Meteorological Society publishes and continually updates an authoritative electronic Meteorology Glossary . Meteorologists work in government agencies , private consulting and research services, industrial enterprises, utilities, radio and television stations , and in education . In the United States, meteorologists held about 10,000 jobs in 2018. Although weather forecasts and warnings are

12880-663: The first weather observing network, that consisted of meteorological stations in Florence , Cutigliano , Vallombrosa , Bologna , Parma , Milan , Innsbruck , Osnabrück , Paris and Warsaw . The collected data were sent to Florence at regular time intervals. In the 1660s Robert Hooke of the Royal Society of London sponsored networks of weather observers. Hippocrates ' treatise Airs, Waters, and Places had linked weather to disease. Thus early meteorologists attempted to correlate weather patterns with epidemic outbreaks, and

13020-508: The first European to have visited the headwaters, modern writers give the credit to the Jesuit Pedro Páez . Páez's account of the source of the Nile is a long and vivid account of Ethiopia. It was published in full only in the early 20th century, although it was featured in works of Páez's contemporaries, including Baltazar Téllez, Athanasius Kircher and Johann Michael Vansleb . Europeans had been resident in Ethiopia since

13160-399: The first time, a practical method for quickly gathering surface weather observations from a wide area. This data could be used to produce maps of the state of the atmosphere for a region near the Earth's surface and to study how these states evolved through time. To make frequent weather forecasts based on these data required a reliable network of observations, but it was not until 1849 that

13300-406: The first to give the correct explanations for the primary rainbow phenomenon. Theoderic went further and also explained the secondary rainbow. By the middle of the sixteenth century, meteorology had developed along two lines: theoretical science based on Meteorologica , and astrological weather forecasting. The pseudoscientific prediction by natural signs became popular and enjoyed protection of

13440-600: The forerunner of the Japan Meteorological Agency , began constructing surface weather maps in 1883. The United States Weather Bureau (1890) was established under the United States Department of Agriculture . The Australian Bureau of Meteorology (1906) was established by a Meteorology Act to unify existing state meteorological services. In 1904, Norwegian scientist Vilhelm Bjerknes first argued in his paper Weather Forecasting as

13580-526: The form of wind. He explained thunder by saying that it was due to ice colliding in clouds, and in Summer it melted. In the thirteenth century, Aristotelian theories reestablished dominance in meteorology. For the next four centuries, meteorological work by and large was mostly commentary . It has been estimated over 156 commentaries on the Meteorologica were written before 1650. Experimental evidence

13720-689: The global climate. Atmospheric physics is the application of physics to the study of the atmosphere. Atmospheric physicists attempt to model Earth's atmosphere and the atmospheres of the other planets using fluid flow equations, chemical models, radiation balancing, and energy transfer processes in the atmosphere and underlying oceans and land. In order to model weather systems, atmospheric physicists employ elements of scattering theory, wave propagation models, cloud physics , statistical mechanics and spatial statistics , each of which incorporate high levels of mathematics and physics. Atmospheric physics has close links to meteorology and climatology and also covers

13860-459: The great lakes. Believing he had found the source of the Nile on seeing this "vast expanse of open water" for the first time, Speke named the lake after Queen Victoria . Burton, recovering from illness and resting further south on the shores of Lake Tanganyika , was outraged that Speke claimed to have proven his discovery to be the true source of the Nile when Burton regarded this as still unsettled. A quarrel ensued which sparked intense debate within

14000-517: The high atmosphere. The Earth's magnetic field and the solar wind interact with the atmosphere, creating the ionosphere , Van Allen radiation belts , telluric currents , and radiant energy . Is a science that bases its more general knowledge of the more specialized disciplines of meteorology, oceanography, geology, and astronomy, which in turn are based on the basic sciences of physics, chemistry, and mathematics. In contrast to meteorology , which studies short term weather systems lasting up to

14140-411: The lack of discipline among weather observers, and the poor quality of the instruments, led the early modern nation states to organise large observation networks. Thus, by the end of the 18th century, meteorologists had access to large quantities of reliable weather data. In 1832, an electromagnetic telegraph was created by Baron Schilling . The arrival of the electrical telegraph in 1837 afforded, for

14280-478: The lakes and the Nile. Hippocrates inquired into the effect of weather on health. Eudoxus claimed that bad weather followed four-year periods, according to Pliny. These early observations would form the basis for Aristotle 's Meteorology , written in 350 BC. Aristotle is considered the founder of meteorology. One of the most impressive achievements described in the Meteorology is the description of what

14420-708: The larger part of which is in Egypt. Below the Aswan Dam , at the northern limit of Lake Nasser, the Nile resumes its historic course. North of Cairo , the Nile splits into two branches (or distributaries) that feed the Mediterranean: the Rosetta Branch to the west and the Damietta to the east, forming the Nile Delta . The annual sediment transport by the Nile in Egypt has been quantified. Below

14560-609: The late 15th century, and one of them may have visited the headwaters even earlier without leaving a written trace. The Portuguese João Bermudes published the first description of the Tis Issat Falls in his 1565 memoirs, compared them to the Nile Falls alluded to in Cicero 's De Republica . Jerónimo Lobo describes the source of the Blue Nile, visiting shortly after Pedro Páez. Telles also uses his account. The White Nile

14700-436: The late 16th century and first half of the 17th century a range of meteorological instruments were invented – the thermometer , barometer , hydrometer , as well as wind and rain gauges. In the 1650s natural philosophers started using these instruments to systematically record weather observations. Scientific academies established weather diaries and organised observational networks. In 1654, Ferdinando II de Medici established

14840-580: The main Nile during the 70,000–80,000 years B.P. wet period. The White Nile system in Bahr El Arab and White Nile Rifts remained a closed lake until the connection of the Victoria Nile to the main system some 12,500 years ago during the African humid period . The Greek historian Herodotus wrote that "Egypt was the gift of the Nile". An unending source of sustenance, it played a crucial role in

14980-441: The mechanical, self-emptying, tipping bucket rain gauge. In 1714, Gabriel Fahrenheit created a reliable scale for measuring temperature with a mercury-type thermometer . In 1742, Anders Celsius , a Swedish astronomer, proposed the "centigrade" temperature scale, the predecessor of the current Celsius scale. In 1783, the first hair hygrometer was demonstrated by Horace-Bénédict de Saussure . In 1802–1803, Luke Howard wrote On

15120-448: The mid-15th century and were respectively the rain gauge , the anemometer, and the hygrometer. Many attempts had been made prior to the 15th century to construct adequate equipment to measure the many atmospheric variables. Many were faulty in some way or were simply not reliable. Even Aristotle noted this in some of his work as the difficulty to measure the air. Sets of surface measurements are important data to meteorologists. They give

15260-552: The night, with change being likely at one of these divisions. Applying the divisions and a principle of balance in the yearly weather, he came up with forecasts like that if a lot of rain falls in the winter, the spring is usually dry. Rules based on actions of animals are also present in his work, like that if a dog rolls on the ground, it is a sign of a storm. Shooting stars and the Moon were also considered significant. However, he made no attempt to explain these phenomena, referring only to

15400-509: The opposite effect. Rene Descartes 's Discourse on the Method (1637) typifies the beginning of the scientific revolution in meteorology. His scientific method had four principles: to never accept anything unless one clearly knew it to be true; to divide every difficult problem into small problems to tackle; to proceed from the simple to the complex, always seeking relationships; to be as complete and thorough as possible with no prejudice. In

15540-621: The past and tries to predict future climate change . Phenomena of climatological interest include the atmospheric boundary layer , circulation patterns , heat transfer ( radiative , convective and latent ), interactions between the atmosphere and the oceans and land surface (particularly vegetation , land use and topography ), and the chemical and physical composition of the atmosphere. Related disciplines include astrophysics , atmospheric physics , chemistry , ecology , physical geography , geology , geophysics , glaciology , hydrology , oceanography , and volcanology . Aeronomy

15680-523: The pattern of atmospheric lows and highs . In 1959, the UK Meteorological Office received its first computer, a Ferranti Mercury . In the 1960s, the chaotic nature of the atmosphere was first observed and mathematically described by Edward Lorenz , founding the field of chaos theory . These advances have led to the current use of ensemble forecasting in most major forecasting centers, to take into account uncertainty arising from

15820-575: The present course of the Nile in Egypt and Sudan. Rushdi Said postulates that Egypt supplied most of the waters of the Nile during the early part of its history. The other theory is that the drainage from Ethiopia via rivers equivalent to the Blue Nile, the Atbara and the Takazze flowed to the Mediterranean via the Egyptian Nile since well back into Tertiary times. Salama suggests that during

15960-415: The prognostic fluid dynamics equations that govern atmospheric flow could be neglected, and a numerical calculation scheme that could be devised to allow predictions. Richardson envisioned a large auditorium of thousands of people performing the calculations. However, the sheer number of calculations required was too large to complete without electronic computers, and the size of the grid and time steps used in

16100-526: The rain as caused by clouds becoming too large for the air to hold, and that clouds became snow if the air was not warm enough to melt them, or hail if they met colder wind. Like his predecessors, Descartes's method was deductive, as meteorological instruments were not developed and extensively used yet. He introduced the Cartesian coordinate system to meteorology and stressed the importance of mathematics in natural science. His work established meteorology as

16240-414: The river flows into the Mediterranean Sea at Alexandria . Egyptian civilization and Sudanese kingdoms have depended on the river and its annual flooding since ancient times. Most of the population and cities of Egypt lie along those parts of the Nile valley north of the Aswan Dam . Nearly all the cultural and historical sites of Ancient Egypt developed and are found along river banks. The Nile is, with

16380-532: The riverbed sufficiently for the river to overflow westward into a depression to create Lake Moeris . Lake Tanganyika drained northwards into the Nile until the Virunga Volcanoes blocked its course in Rwanda. The Nile was much longer at that time, with its furthest headwaters in northern Zambia. The currently existing Nile first flowed during the former parts of the Würm glaciation period. Affad 23

16520-475: The science of meteorology. Meteorological phenomena are described and quantified by the variables of Earth's atmosphere: temperature, air pressure, water vapour , mass flow , and the variations and interactions of these variables, and how they change over time. Different spatial scales are used to describe and predict weather on local, regional, and global levels. Meteorology, climatology , atmospheric physics , and atmospheric chemistry are sub-disciplines of

16660-407: The scientific community and interest by other explorers keen to either confirm or refute Speke's discovery. British explorer and missionary David Livingstone pushed too far west and entered the Congo River system instead. It was ultimately Welsh-American explorer Henry Morton Stanley who confirmed Speke's discovery, circumnavigating Lake Victoria and reporting the great outflow at Ripon Falls on

16800-441: The scientific revolution in meteorology. Speculation on the cause of the flooding of the Nile ended when Eratosthenes , according to Proclus , stated that it was known that man had gone to the sources of the Nile and observed the rains, although interest in its implications continued. During the era of Roman Greece and Europe, scientific interest in meteorology waned. In the 1st century BC, most natural philosophers claimed that

16940-588: The sea level rose at the end of the most recent ice age , the stream which is now the northern Nile captured the ancestral Nile near Asyut . This change in climate also led to the current extents of the Sahara desert, around 3400 BCE. The Giza pyramid complex originally overlooked a branch of the Nile that no longer exists. This branch was highest during the African Humid Period . The existing Nile has five earlier phases: Flowing north from

17080-440: The seasons. He believed that fire and water opposed each other in the atmosphere, and when fire gained the upper hand, the result was summer, and when water did, it was winter. Democritus also wrote about the flooding of the Nile. He said that during the summer solstice, snow in northern parts of the world melted. This would cause vapors to form clouds, which would cause storms when driven to the Nile by northerly winds, thus filling

17220-597: The second oldest national meteorological service in the world (the Central Institution for Meteorology and Geodynamics (ZAMG) in Austria was founded in 1851 and is the oldest weather service in the world). The first daily weather forecasts made by FitzRoy's Office were published in The Times newspaper in 1860. The following year a system was introduced of hoisting storm warning cones at principal ports when

17360-421: The smaller planets lose these gases into space . The composition of the Earth's atmosphere is different from the other planets because the various life processes that have transpired on the planet have introduced free molecular oxygen . Much of Mercury's atmosphere has been blasted away by the solar wind . The only moon that has retained a dense atmosphere is Titan . There is a thin atmosphere on Triton , and

17500-484: The soil. The Nile no longer floods in Egypt since the completion of the Aswan Dam in 1970. An anabranch river, the Bahr el Zeraf , flows out of the Nile's Bahr al Jabal section and rejoins the White Nile. The flow rate of the Bahr al Jabal at Mongalla is almost constant throughout the year and averages 1,048 m /s (37,000 cu ft/s). After Mongalla, the Bahr Al Jabal enters the enormous swamps of

17640-643: The star's energy around the planet. Nile The Nile (also known as the River Nile or Nile River ) is a major north-flowing river in northeastern Africa . It flows into the Mediterranean Sea . The Nile is the longest river in Africa. It has historically been considered the longest river in the world , though this has been contested by research suggesting that the Amazon River

17780-515: The term Nil ( Sanskrit : नील , romanized :  nila ; Egyptian Arabic : نيلة ), which refers to Indigofera tinctoria , one of the original sources of indigo dye . Another may be Nymphaea caerulea , known as "The Sacred Blue Lily of the Nile", which was found scattered over Tutankhamun 's corpse when it was excavated in 1922. Another possible etymology derives from the Semitic term Nahal , meaning "river". Old Libyan has

17920-422: The term lilu , meaning water (in modern Berber ilel ⵉⵍⴻⵍ means sea ). With a total length of about 6,650 km (4,130 mi) between the region of Lake Victoria and the Mediterranean Sea , the Nile is among the longest rivers on Earth. The drainage basin of the Nile covers 3,254,555 square kilometers (1,256,591 sq mi), about 10% of the area of Africa. Compared to other major rivers, though,

18060-433: The unique, local, or broad effects within those subclasses. Atmospheric science Experimental instruments used in atmospheric science include satellites , rocketsondes , radiosondes , weather balloons , radars , and lasers . The term aerology (from Greek ἀήρ, aēr , " air "; and -λογία, -logia ) is sometimes used as an alternative term for the study of Earth's atmosphere; in other definitions, aerology

18200-589: The value of his work is in preserving earlier speculation, much like Seneca's work. From 400 to 1100, scientific learning in Europe was preserved by the clergy. Isidore of Seville devoted a considerable attention to meteorology in Etymologiae , De ordine creaturum and De natura rerum . Bede the Venerable was the first Englishman to write about the weather in De Natura Rerum in 703. The work

18340-480: The word ⲫⲓⲁⲣⲟ , pronounced piaro ( Sahidic ) or phiaro ( Bohairic ), means "the river" (lit. p(h).iar-o "the.canal-great"), and comes from the same ancient name. In Nobiin , the river is called Áman Dawū , meaning "the great water". In Luganda , the river is called Kiira or Kiyira . In Runyoro , it is called Kihiira . In Egyptian Arabic , the Nile is called en-Nīl , while in Standard Arabic it

18480-415: Was a summary of then extant classical sources. However, Aristotle's works were largely lost until the twelfth century, including Meteorologica . Isidore and Bede were scientifically minded, but they adhered to the letter of Scripture . Islamic civilization translated many ancient works into Arabic which were transmitted and translated in western Europe to Latin. In the 9th century, Al-Dinawari wrote

18620-469: Was considered a subset of astronomy. He gave several astrological weather predictions. He constructed a map of the world divided into climatic zones by their illumination, in which the length of the Summer solstice increased by half an hour per zone between the equator and the Arctic. Ptolemy wrote on the atmospheric refraction of light in the context of astronomical observations. In 25 AD, Pomponius Mela ,

18760-574: Was enough to fill and connect them. The Egyptian Nile connected to the Sudanese Nile, which captures the Ethiopian and Equatorial headwaters during the current stages of tectonic activity in the Eastern, Central and Sudanese Rift systems. The connection of the different Niles occurred during cyclic wet periods. The Atbarah overflowed its closed basin during the wet periods that occurred about 100,000 to 120,000 years ago. The Blue Nile connected to

18900-597: Was even less understood. The ancients mistakenly believed that the Niger River represented the upper reaches of the White Nile. For example, Pliny the Elder writes that the Nile had its origins "in a mountain of lower Mauretania ", flowed above ground for "many days" distance, then went underground, reappeared as a large lake in the territories of the Masaesyli , then sank again below the desert to flow underground "for

19040-427: Was less important than appeal to the classics and authority in medieval thought. In the thirteenth century, Roger Bacon advocated experimentation and the mathematical approach. In his Opus majus , he followed Aristotle's theory on the atmosphere being composed of water, air, and fire, supplemented by optics and geometric proofs. He noted that Ptolemy's climatic zones had to be adjusted for topography . St. Albert

19180-404: Was not generally accepted for centuries. A theory to explain summer hail was first proposed by Anaxagoras . He observed that air temperature decreased with increasing height and that clouds contain moisture. He also noted that heat caused objects to rise, and therefore the heat on a summer day would drive clouds to an altitude where the moisture would freeze. Empedocles theorized on the change of

19320-589: Was not until after the elucidation of the laws of physics, and more particularly in the latter half of the 20th century, the development of the computer (allowing for the automated solution of a great many modelling equations) that significant breakthroughs in weather forecasting were achieved. An important branch of weather forecasting is marine weather forecasting as it relates to maritime and coastal safety, in which weather effects also include atmospheric interactions with large bodies of water. Meteorological phenomena are observable weather events that are explained by

19460-399: Was the first work to challenge fundamental aspects of Aristotelian theory. Cardano maintained that there were only three basic elements- earth, air, and water. He discounted fire because it needed material to spread and produced nothing. Cardano thought there were two kinds of air: free air and enclosed air. The former destroyed inanimate things and preserved animate things, while the latter had

19600-533: Was written by George Hadley . In 1743, when Benjamin Franklin was prevented from seeing a lunar eclipse by a hurricane , he decided that cyclones move in a contrary manner to the winds at their periphery. Understanding the kinematics of how exactly the rotation of the Earth affects airflow was partial at first. Gaspard-Gustave Coriolis published a paper in 1835 on the energy yield of machines with rotating parts, such as waterwheels. In 1856, William Ferrel proposed

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