Misplaced Pages

#890109

70-456: Gazelles , oryx , sand cats , and spiny-tailed lizards are just some of the desert-adapted species that survive in this extreme environment, which features everything from red dunes to deadly quicksand . The climate is mostly dry (the major part receives around 100 mm (3.9 in) of rain per year, but some very rare places receive as little as 50 mm), and temperatures oscillate between very high heat and seasonal night time freezes. It

140-402: A change in temperature. The numbers are exactly equal if we consider the gases as ideal . The addition of water molecules, or any other molecules, to a gas, without removal of an equal number of other molecules, will necessarily require a change in temperature, pressure, or total volume; that is, a change in at least one of these three parameters. If temperature and pressure remain constant,

210-512: A distinctive behaviour of stotting (running and jumping high before fleeing) when they are threatened by predators such as cheetahs , lions , African wild dogs , crocodiles , hyenas , and leopards . Gazelle is derived from French gazelle , Old French gazel , probably via Old Spanish gacel , probably from North African pronunciation of Arabic : غزال ġazāl , Maghrebi pronunciation ġazēl . To Europe it first came to Old Spanish and Old French , and then around 1600

280-433: A much lower scale height and shorter atmospheric lifetime — weeks instead of decades. Without other greenhouse gases, Earth's blackbody temperature , below the freezing point of water, would cause water vapor to be removed from the atmosphere. Water vapor is thus a "slave" to the non-condensible greenhouse gases. Humidity is one of the fundamental abiotic factors that defines any habitat (the tundra, wetlands, and

350-419: A non-condensable phase other than air. A device used to measure humidity of air is called a psychrometer or hygrometer . A humidistat is a humidity-triggered switch, often used to control a humidifier or a dehumidifier . The humidity of an air and water vapor mixture is determined through the use of psychrometric charts if both the dry bulb temperature ( T ) and the wet bulb temperature ( T w ) of

420-525: A relatively high humidity post-rainfall. Outside the monsoon seasons, humidity is high (in comparison to countries further from the Equator), but completely sunny days abound. In cooler places such as Northern Tasmania, Australia, high humidity is experienced all year due to the ocean between mainland Australia and Tasmania. In the summer the hot dry air is absorbed by this ocean and the temperature rarely climbs above 35 °C (95 °F). Humidity affects

490-588: A sustained speed of 50 km/h (30 mph). Gazelles are found mostly in the deserts, grasslands, and savannas of Africa , but they are also found in southwest and central Asia and the Indian subcontinent . They tend to live in herds, and eat fine, easily digestible plants and leaves. Gazelles are relatively small antelopes, most standing 60–110 cm (2–3.5 ft) high at the shoulder, and are generally fawn-colored . The gazelle genera are Gazella , Eudorcas , and Nanger . The taxonomy of these genera

560-412: Is affected by winds and by rainfall. The most humid cities on Earth are generally located closer to the equator, near coastal regions. Cities in parts of Asia and Oceania are among the most humid. Bangkok, Ho Chi Minh City , Kuala Lumpur , Hong Kong, Manila , Jakarta , Naha , Singapore, Kaohsiung and Taipei have very high humidity most or all year round because of their proximity to water bodies and

630-434: Is almost independent of the amount of air (nitrogen, oxygen, etc.) that is present. Indeed, a vacuum has approximately the same equilibrium capacity to hold water vapor as the same volume filled with air; both are given by the equilibrium vapor pressure of water at the given temperature. There is a very small difference described under "Enhancement factor" below, which can be neglected in many calculations unless great accuracy

700-435: Is also a key metric used to evaluate when it is appropriate to install flooring over a concrete slab. Specific humidity (or moisture content) is the ratio of the mass of water vapor to the total mass of the air parcel. Specific humidity is approximately equal to the mixing ratio , which is defined as the ratio of the mass of water vapor in an air parcel to the mass of dry air for the same parcel. As temperature decreases,

770-487: Is also measured on a global scale using remotely placed satellites. These satellites are able to detect the concentration of water in the troposphere at altitudes between 4 and 12 km (2.5 and 7.5 mi). Satellites that can measure water vapor have sensors that are sensitive to infrared radiation . Water vapor specifically absorbs and re-radiates radiation in this spectral band. Satellite water vapor imagery plays an important role in monitoring climate conditions (like

SECTION 10

#1732765040891

840-543: Is an important metric used in weather forecasts and reports, as it is an indicator of the likelihood of precipitation , dew, or fog. In hot summer weather, a rise in relative humidity increases the apparent temperature to humans (and other animals) by hindering the evaporation of perspiration from the skin. For example, according to the heat index , a relative humidity of 75% at air temperature of 80.0 °F (26.7 °C) would feel like 83.6 ± 1.3 °F (28.7 ± 0.7 °C). Relative humidity

910-516: Is confused, and the classification of species and subspecies has been an unsettled issue. Currently, the genus Gazella is widely considered to contain about 10 species. One subspecies is extinct: the Queen of Sheba's gazelle . Most surviving gazelle species are considered threatened to varying degrees. Closely related to the true gazelles are the Tibetan goa , and Mongolian gazelles (species of

980-460: Is defined as the ratio of the partial pressure of water vapor ( p {\displaystyle p} ) in air to the saturation vapor pressure ( p s {\displaystyle p_{s}} ) of water at the same temperature, usually expressed as a percentage: φ = 100 % ⋅ p / p s {\displaystyle \varphi =100\%\cdot p/p_{s}} Relative humidity

1050-627: Is expressed as either mass of water vapor per volume of moist air (in grams per cubic meter) or as mass of water vapor per mass of dry air (usually in grams per kilogram). Relative humidity , often expressed as a percentage, indicates a present state of absolute humidity relative to a maximum humidity given the same temperature. Specific humidity is the ratio of water vapor mass to total moist air parcel mass. Humidity plays an important role for surface life. For animal life dependent on perspiration (sweating) to regulate internal body temperature, high humidity impairs heat exchange efficiency by reducing

1120-407: Is generally invisible to the human eye. Humidity indicates the likelihood for precipitation , dew , or fog to be present. Humidity depends on the temperature and pressure of the system of interest. The same amount of water vapor results in higher relative humidity in cool air than warm air. A related parameter is the dew point . The amount of water vapor needed to achieve saturation increases as

1190-430: Is inappropriate for computations in chemical engineering, such as drying, where temperature variations might be significant. As a result, absolute humidity in chemical engineering may refer to mass of water vapor per unit mass of dry air, also known as the humidity ratio or mass mixing ratio (see "specific humidity" below), which is better suited for heat and mass balance calculations. Mass of water per unit volume as in

1260-438: Is one of many antelope species in the genus Gazella / ɡ ə ˈ z ɛ l ə / . There are also seven species included in two further genera; Eudorcas and Nanger , which were formerly considered subgenera of Gazella . A third former subgenus, Procapra , includes three living species of Asian gazelles. Gazelles are known as swift animals. Some can run at bursts as high as 100 km/h (60 mph) or run at

1330-567: Is part of the deserts and xeric shrublands biome and lie in biogeographical realms of the Palearctic (northern part) and Afrotropical (southern part). The Arabian Desert ecoregion has little biodiversity , although a few endemic plants grow here. Many species, such as the striped hyena , jackal and honey badger , have died out as a result of hunting , habitat destruction , overgrazing by livestock, off-road driving , and human encroachment on their habitat. Other species, such as

1400-847: Is related, is the totem of many African families. Some examples include the Joof family of the Senegambia region , the Bagananoa of Botswana in Southern Africa (said to be descended from the BaHurutshe), and the Eraraka (or Erarak) clan of Uganda . As is common in many African societies, it is forbidden for the Joof or Eraraka to kill or touch the family totem. One of the traditional themes of Arabic love poetry involves comparing

1470-528: Is required. Absolute humidity is the total mass of water vapor (gas form of water) present in a given volume or mass of air. It does not take temperature into consideration. Absolute humidity in the atmosphere ranges from near zero to roughly 30 g (1.1 oz) per cubic metre when the air is saturated at 30 °C (86 °F). Absolute humidity is the mass of the water vapor ( m H 2 O ) {\displaystyle (m_{{\text{H}}_{2}{\text{O}}})} , divided by

SECTION 20

#1732765040891

1540-556: Is shown in State B. If the system at State A is isothermally compressed (compressed with no change in system temperature), then the relative humidity of the system increases because the partial pressure of water in the system increases with the volume reduction. This is shown in State C. Above 202.64 kPa, the RH would exceed 100% and water may begin to condense. If the pressure of State A was changed by simply adding more dry air, without changing

1610-450: Is the dry-bulb temperature expressed in degrees Celsius (°C), P {\displaystyle P} is the absolute pressure expressed in millibars, and e w ∗ {\displaystyle e_{w}^{*}} is the equilibrium vapor pressure expressed in millibars. Buck has reported that the maximal relative error is less than 0.20% between −20 and +50 °C (−4 and 122 °F) when this particular form of

1680-558: Is the most abundant of all greenhouse gases . Water vapor, like a green lens that allows green light to pass through it but absorbs red light, is a "selective absorber". Like the other greenhouse gasses, water vapor is transparent to most solar energy. However, it absorbs the infrared energy emitted (radiated) upward by the Earth's surface, which is the reason that humid areas experience very little nocturnal cooling but dry desert regions cool considerably at night. This selective absorption causes

1750-437: Is the ratio of how much water vapour is in the air to how much water vapour the air could potentially contain at a given temperature. It varies with the temperature of the air: colder air can contain less vapour, and water will tend to condense out of the air more at lower temperatures. So changing the temperature of air can change the relative humidity, even when the absolute humidity remains constant. Chilling air increases

1820-785: The Arabian sand gazelle , have been successfully re-introduced and are protected at reserves. The desert lies mostly in Saudi Arabia and covers most of the country. It extends into neighboring southern Iraq , southern Jordan , central Qatar , most of the Abu Dhabi emirate in the United Arab Emirates , western Oman , and northeastern Yemen . The ecoregion also includes most of the Sinai Peninsula in Egypt and

1890-629: The Magnus–Tetens approximation , are more complicated but yield better accuracy. The Arden Buck equation is commonly encountered in the literature regarding this topic: e w ∗ = ( 1.0007 + 3.46 × 10 − 6 P ) × 6.1121 e 17.502 T / ( 240.97 + T ) , {\displaystyle e_{w}^{*}=\left(1.0007+3.46\times 10^{-6}P\right)\times 6.1121\,e^{17.502T/(240.97+T)},} where T {\displaystyle T}

1960-425: The energy budget and thereby influences temperatures in two major ways. First, water vapor in the atmosphere contains "latent" energy. During transpiration or evaporation, this latent heat is removed from surface liquid, cooling the Earth's surface. This is the biggest non-radiative cooling effect at the surface. It compensates for roughly 70% of the average net radiative warming at the surface. Second, water vapor

2030-526: The monsoon season. High temperatures combine with the high dew point to create heat index in excess of 65 °C (149 °F). Darwin experiences an extremely humid wet season from December to April. Houston, Miami, San Diego, Osaka, Shanghai, Shenzhen and Tokyo also have an extreme humid period in their summer months. During the South-west and North-east Monsoon seasons (respectively, late May to September and November to March), expect heavy rains and

2100-635: The quicksands of Umm al Samim . The Wahiba Sands of Oman are an isolated sand sea bordering the east coast . The Arabian Desert has a subtropical , hot desert climate , similar to the climate of the Sahara Desert (the world's largest hot desert). The Arabian Desert is actually an extension of the Sahara Desert over the Arabian peninsula. The climate is mainly dry. Most areas get around 100 mm (3.9 in) of rain per year. Unlike

2170-566: The Arabian Desert. The ecoregion is home to 310 bird species. The area is home to several different cultures, languages, and peoples, with Islam as the predominant faith. The major ethnic group in the region is the Arabs , whose primary language is Arabic . In the center of the desert lies Riyadh , the capital of Saudi Arabia, with more than 7 million inhabitants. Other large cities, such as Dubai , Abu Dhabi , or Kuwait City , lie on

Arabian Desert - Misplaced Pages Continue

2240-616: The Sahara Desert—more than half of which is hyperarid (having rainfall of less than 50 mm (2.0 in) per year)—the Arabian Desert has only a few hyperarid areas. These rare driest areas may get only 30 to 40 mm (1.6 in) of rain per year. The Arabian Desert’s sunshine duration index is very high by global standards: between 2,900 hours (66.2% of daylight hours) and 3,600 hours (82.1% of daylight hours), but typically around 3,400 hours (77.6% of daylight hours). Thus clear-sky conditions with plenty of sunshine prevail over

2310-646: The adjacent Negev desert in southern Israel. The Rub' al-Khali desert is a sedimentary basin stretching along a south-west to north-east axis across the Arabian Shelf. At an altitude of 1,000 metres (3,300 ft), rock landscapes yield to the Rub' al-Khali, a vast stretch of sand whose extreme southern point crosses the center of Yemen. The sand overlies gravel or gypsum plains and the dunes reach maximum heights of up to 250 m (820 ft). The sands are predominantly silicates, composed of 80 to 90% quartz and

2380-424: The amount of water vapor needed to reach saturation also decreases. As the temperature of a parcel of air becomes lower it will eventually reach the point of saturation without adding or losing water mass. The term relative humidity is reserved for systems of water vapor in air. The term relative saturation is used to describe the analogous property for systems consisting of a condensable phase other than water in

2450-663: The atmosphere is as warm or warmer than the skin during times of high humidity, blood brought to the body surface cannot dissipate heat by conduction to the air. With so much blood going to the external surface of the body, less goes to the active muscles, the brain, and other internal organs. Physical strength declines, and fatigue occurs sooner than it would otherwise. Alertness and mental capacity also may be affected, resulting in heat stroke or hyperthermia . Domesticated plants and animals (e.g. lizards) require regular upkeep of humidity percent when grown in-home and container conditions, for optimal thriving environment. Although humidity

2520-448: The chilled mirror method is effective. For process on-line measurements, the most commonly used sensors nowadays are based on capacitance measurements to measure relative humidity, frequently with internal conversions to display absolute humidity as well. These are cheap, simple, generally accurate and relatively robust. All humidity sensors face problems in measuring dust-laden gas, such as exhaust streams from clothes dryers. Humidity

2590-621: The coast of the Persian Gulf . Natural resources available in the Arabian Desert include oil , natural gas , phosphates , and sulfur . Threats to the ecoregion include overgrazing by livestock and feral camels and goats, wildlife poaching , and damage to vegetation by off-road driving. The conservation status of the desert is critical/endangered. In the UAE, the sand gazelle and Arabian oryx are threatened, and honey badgers , jackals , and striped hyaenas already extirpated. 4.37% of

2660-415: The desert are a few examples), and is a determinant of which animals and plants can thrive in a given environment. The human body dissipates heat through perspiration and its evaporation. Heat convection , to the surrounding air, and thermal radiation are the primary modes of heat transport from the body. Under conditions of high humidity, the rate of evaporation of sweat from the skin decreases. Also, if

2730-661: The ecoregion is in protected areas. Saudi Arabia has established a system of reserves overseen by the National Commission for Wildlife Conservation and Development (NCWCD). Protected areas in the United Arab Emirates include Al Houbara Protected Area (2492.0 km), Al Ghadha Protected Area (1087.51 km), Arabian Oryx Protected Area (5974.47 km), Ramlah Protected Area (544.44 km), and Al Beda'a Protected Area (417.0 km). Gazelle Several, see text A gazelle

2800-465: The enhancement factor is normally slightly greater than unity for real systems. The enhancement factor is commonly used to correct the equilibrium vapor pressure of water vapor when empirical relationships, such as those developed by Wexler, Goff, and Gratch, are used to estimate the properties of psychrometric systems. Buck has reported that, at sea level, the vapor pressure of water in saturated moist air amounts to an increase of approximately 0.5% over

2870-443: The equation above is also defined as volumetric humidity . Because of the potential confusion, British Standard BS 1339 suggests avoiding the term "absolute humidity". Units should always be carefully checked. Many humidity charts are given in g/kg or kg/kg, but any mass units may be used. The field concerned with the study of physical and thermodynamic properties of gas–vapor mixtures is named psychrometrics . Relative humidity

Arabian Desert - Misplaced Pages Continue

2940-590: The equator and often overcast weather. Some places experience extreme humidity during their rainy seasons combined with warmth giving the feel of a lukewarm sauna, such as Kolkata , Chennai and Kochi in India, and Lahore in Pakistan. Sukkur city located on the Indus River in Pakistan has some of the highest and most uncomfortable dew points in the country, frequently exceeding 30 °C (86 °F) in

3010-474: The equilibrium vapor pressure of pure water. Climate control refers to the control of temperature and relative humidity in buildings, vehicles and other enclosed spaces for the purpose of providing for human comfort, health and safety, and of meeting environmental requirements of machines, sensitive materials (for example, historic) and technical processes. While humidity itself is a climate variable, it also affects other climate variables. Environmental humidity

3080-418: The formation of thunderstorms) and in the development of weather forecasts . Humidity depends on water vaporization and condensation, which, in turn, mainly depends on temperature. Therefore, when applying more pressure to a gas saturated with water, all components will initially decrease in volume approximately according to the ideal gas law . However, some of the water will condense until returning to almost

3150-538: The gazelle with the beloved, and linguists theorize ghazal , the word for love poetry in Arabic, is related to the word for gazelle. It is related that the Caliph Abd al-Malik (646–705) freed a gazelle that he had captured because of her resemblance to his beloved: O likeness of Layla , never fear! For I am your friend, today, O wild gazelle! Then I say, after freeing her from her fetters: You are free for

3220-409: The generalized formula is used to estimate the equilibrium vapor pressure of water. There are various devices used to measure and regulate humidity. Calibration standards for the most accurate measurement include the gravimetric hygrometer, chilled mirror hygrometer , and electrolytic hygrometer. The gravimetric method, while the most accurate, is very cumbersome. For fast and very accurate measurement

3290-489: The genus Procapra ), the blackbuck of Asia, and the African springbok . One widely familiar gazelle is the African species Thomson's gazelle ( Eudorcas thomsonii ), sometimes referred to as a "tommie". It is around 60 to 70 cm (24 to 28 in) in shoulder height and is coloured brown and white with a distinguishing black stripe. The males have long, often curved, horns. Like many other prey species, tommies exhibit

3360-603: The genus. The earliest members of the genus are known from the Middle Miocene of Africa, around 14 million years ago with members of the genus inhabiting Europe from the Late Miocene until their extinction in the region during the Early Pleistocene around 1.8 million years ago. Humidity Humidity is the concentration of water vapor present in the air. Water vapor, the gaseous state of water,

3430-450: The greenhouse effect. It raises the surface temperature substantially above its theoretical radiative equilibrium temperature with the sun, and water vapor is the cause of more of this warming than any other greenhouse gas. Unlike most other greenhouse gases, however, water is not merely below its boiling point in all regions of the Earth, but below its freezing point at many altitudes. As a condensible greenhouse gas, it precipitates , with

3500-440: The ideal gas law. On the contrary the saturated volume is the volume a gas mixture would have if humidity was added to it until saturation (or 100% relative humidity). Humid air is less dense than dry air because a molecule of water ( m ≈ 18  Da ) is less massive than either a molecule of nitrogen ( m ≈ 28 ) or a molecule of oxygen ( m ≈ 32 ). About 78% of the molecules in dry air are nitrogen (N 2 ). Another 21% of

3570-414: The measure of relative humidity of the air, although their presence is an indication that a body of air may be close to the dew point. Relative humidity is normally expressed as a percentage; a higher percentage means that the air–water mixture is more humid. At 100% relative humidity, the air is saturated and is at its dew point. In the absence of a foreign body on which droplets or crystals can nucleate ,

SECTION 50

#1732765040891

3640-456: The mixture are known. These quantities are readily estimated by using a sling psychrometer . There are several empirical formulas that can be used to estimate the equilibrium vapor pressure of water vapor as a function of temperature. The Antoine equation is among the least complex of these, having only three parameters ( A , B , and C ). Other formulas, such as the Goff–Gratch equation and

3710-444: The molecules in dry air are oxygen (O 2 ). The final 1% of dry air is a mixture of other gases. For any gas, at a given temperature and pressure, the number of molecules present in a particular volume is constant. Therefore, when some number N of water molecules (vapor) is introduced into a volume of dry air, the number of air molecules in that volume must decrease by the same number N for the pressure to remain constant without using

3780-756: The outer margin (typically Acacia ehrenbergiana , Vachellia tortilis , Balanites aegyptiaca , Olea europaea , Cupressus sempervirens , and Prosopis cineraria ). Other species are a woody perennial Calligonum comosum , and annual herbs such as Danthonia forskallii . There are 102 native species of mammals. Native mammals include the Arabian oryx ( Oryx leucoryx ), sand gazelle ( Gazella marica ), mountain gazelle ( G. gazella ), Nubian ibex ( Capra nubiana ), Arabian wolf ( Canis lupus arabs ), striped hyaena ( Hyaena hyaena ), caracal ( Caracal caracal ), sand cat ( Felis margarita ), red fox ( Vulpes vulpes ), and Cape hare ( Lepus capensis ). The Asiatic cheetah and Asiatic lion used to live in

3850-417: The rate of moisture evaporation from skin surfaces. This effect can be calculated using a heat index table, or alternatively using a similar humidex . The notion of air "holding" water vapor or being "saturated" by it is often mentioned in connection with the concept of relative humidity. This, however, is misleading—the amount of water vapor that enters (or can enter) a given space at a given temperature

3920-618: The region throughout the year, and cloudy periods are infrequent. Visibility at ground level is relatively low, despite the brightness of the sun and moon, because of dust and humidity . Temperatures remain high year round. In the summer, in low-lying areas, average high temperatures are generally over 40 °C (104 °F). In extremely low-lying areas, especially along the Persian Gulf (near sea level), summer temperatures can reach 48 °C (118 °F). Average low temperatures in summer are typically over 20 °C (68 °F) and in

3990-491: The relative humidity can exceed 100%, in which case the air is said to be supersaturated . Introduction of some particles or a surface to a body of air above 100% relative humidity will allow condensation or ice to form on those nuclei, thereby removing some of the vapour and lowering the humidity. In a scientific notion, the relative humidity ( R H {\displaystyle RH} or φ {\displaystyle \varphi } ) of an air-water mixture

4060-440: The relative humidity, and can cause the water vapour to condense (if the relative humidity rises over 100%, the dew point ). Likewise, warming air decreases the relative humidity. Warming some air containing a fog may cause that fog to evaporate, as the droplets are prone to total evaporation due to the heat. Relative humidity only considers the invisible water vapour. Mists, clouds, fogs and aerosols of water do not count towards

4130-562: The remainder feldspar, whose iron oxide-coated grains color the sands orange, purple, and red. A corridor of sandy terrain known as the Ad-Dahna desert connects the An-Nafud desert (65,000 km or 40,389 square miles) in the north of Saudi Arabia to the Rub' al-Khali in the south-east. The Tuwaiq escarpment is an 800 km (500 mi) arc that includes limestone cliffs, plateaus, and canyons. There are brackish salt flats, including

4200-498: The sake of Layla, for ever! The theme is found in the ancient Hebrew Song of Songs . (8:14) Come away, my beloved, and be like a gazelle or like a young stag on the spice-laden mountains. The gazelles are divided into three genera and numerous species. Fossils of genus Gazella are found in Miocene , Pliocene and Pleistocene deposits of Eurasia and Africa, which occupuied a broader distribution that modern members of

4270-403: The same humidity as before, giving the resulting total volume deviating from what the ideal gas law predicted. Conversely, decreasing temperature would also make some water condense, again making the final volume deviate from predicted by the ideal gas law. Therefore, gas volume may alternatively be expressed as the dry volume, excluding the humidity content. This fraction more accurately follows

SECTION 60

#1732765040891

4340-495: The sands and 17 around the outer margins. Of these 37 species, one or two are endemic. Vegetation is very diffuse but fairly evenly distributed, with some interruptions of near sterile dunes. Some typical plants are Calligonum crinitum on dune slopes, Cornulaca arabica (saltbush), Salsola stocksii (saltbush), and Cyperus conglomeratus . Other widespread species are Dipterygium glaucum , Limeum arabicum , and Zygophyllum mandavillei . Very few trees are found except at

4410-502: The saturated vapor pressure of pure water: f W = e w ′ e w ∗ . {\displaystyle f_{W}={\frac {e'_{w}}{e_{w}^{*}}}.} The enhancement factor is equal to unity for ideal gas systems. However, in real systems the interaction effects between gas molecules result in a small increase of the equilibrium vapor pressure of water in air relative to equilibrium vapor pressure of pure water vapor. Therefore,

4480-401: The south can sometimes exceed 30 °C (86 °F). Record high temperatures above 50 °C (122 °F) have been reached in many areas of the desert, partly because its overall elevation is relatively low. The Arabian Desert ecoregion has about 900 species of plants. The Rub'al-Khali has very limited floristic diversity . There are only 37 plant species, 20 recorded in the main body of

4550-463: The temperature but also on the absolute pressure of the system of interest. This dependence is demonstrated by considering the air–water system shown below. The system is closed (i.e., no matter enters or leaves the system). If the system at State A is isobarically heated (heating with no change in system pressure), then the relative humidity of the system decreases because the equilibrium vapor pressure of water increases with increasing temperature. This

4620-553: The temperature increases. As the temperature of a parcel of air decreases it will eventually reach the saturation point without adding or losing water mass. The amount of water vapor contained within a parcel of air can vary significantly. For example, a parcel of air near saturation may contain 8 g of water per cubic metre of air at 8 °C (46 °F), and 28 g of water per cubic metre of air at 30 °C (86 °F) Three primary measurements of humidity are widely employed: absolute, relative, and specific. Absolute humidity

4690-416: The volume increases, and the dry air molecules that were displaced will initially move out into the additional volume, after which the mixture will eventually become uniform through diffusion. Hence the mass per unit volume of the gas—its density—decreases. Isaac Newton discovered this phenomenon and wrote about it in his book Opticks . The relative humidity of an air–water system is dependent not only on

4760-468: The volume of the air and water vapor mixture ( V net ) {\displaystyle (V_{\text{net}})} , which can be expressed as: A H = m H 2 O V net . {\displaystyle AH={\frac {m_{{\text{H}}_{2}{\text{O}}}}{V_{\text{net}}}}.} If the volume is not set, the absolute humidity varies with changes in air temperature or pressure. Because of this, it

4830-499: The volume, the relative humidity would not change. Therefore, a change in relative humidity can be explained by a change in system temperature, a change in the volume of the system, or change in both of these system properties. The enhancement factor ( f w ) {\displaystyle (f_{w})} is defined as the ratio of the saturated vapor pressure of water in moist air ( e w ′ ) {\displaystyle (e'_{w})} to

4900-510: The word entered the English language . The Arab people traditionally hunted the gazelle. Later appreciated for its grace, however, it became a symbol most commonly associated in Arabic literature with human female beauty. In many countries in northwestern Sub-Saharan Africa , the gazelle is commonly referred to as "dangelo", meaning "swift deer". The gazelle, like the antelope to which it

#890109