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115-838: The United States Botanic Garden ( USBG ) is a botanical garden on the grounds of the United States Capitol in Washington, D.C. , near the James A. Garfield Monument . The Botanic Garden is supervised by the Congress through the Architect of the Capitol , who is responsible for maintaining the grounds of the United States Capitol. The USBG is open every day of the year, including federal holidays . It

230-736: A water garden in memory of the First Ladies of the United States .The National Garden construction was funded by the National Fund for the U.S. Botanic Garden which now exists as a 'friends group'. Bartholdi Park lies just south of the Conservatory, across Independence Avenue. It is named for the Bartholdi Fountain in the garden's center designed by Frédéric Auguste Bartholdi . One of the goals of this garden

345-491: A botanical garden is defined by its scientific or academic connection, then the first true botanical gardens were established with the revival of learning that occurred in the European Renaissance . These were secular gardens attached to universities and medical schools, used as resources for teaching and research. The superintendents of these gardens were often professors of botany with international reputations,

460-402: 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,

575-403: A department of an educational institution, it may be related to a teaching program. In any case, it exists for scientific ends and is not to be restricted or diverted by other demands. It is not merely a landscaped or ornamental garden, although it may be artistic, nor is it an experiment station or yet a park with labels on the plants. The essential element is the intention of the enterprise, which

690-528: A factor that probably contributed to the creation of botany as an independent discipline rather than a descriptive adjunct to medicine. The botanical gardens of Southern Europe were associated with university faculties of medicine and were founded in Italy at Orto botanico di Pisa (1544), Orto botanico di Padova (1545), Orto Botanico di Firenze (1545), Orto Botanico dell'Università di Pavia (1558) and Orto Botanico dell'Università di Bologna (1568). Here

805-674: A misting system, retractable shades and levered windows. All plants are watered daily by hand. Construction was completed on the 3-acre (12,000 m) National Garden on the Botanic Garden's west border, in October 2006 and the garden includes a regional garden of plants native to the Atlantic Coastal Plain and Piedmont, a rose garden , a butterfly garden , and the First Ladies Water Garden,

920-433: 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

1035-419: 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

1150-538: A period of prosperity when the city was a trading centre for the Dutch East India Company . Other gardens were constructed in Brazil ( Rio de Janeiro Botanical Garden , 1808), Sri Lanka ( Botanic Gardens of Peradeniya , 1821 and on a site dating back to 1371), Indonesia ( Bogor Botanical Gardens , 1817 and Kebun Raya Cibodas , 1852), and Singapore ( Singapore Botanical Gardens , 1822). These had

1265-608: A profound effect on the economy of the countries, especially in relation to the foods and medicines introduced. The importation of rubber trees to the Singapore Botanic Garden initiated the important rubber industry of the Malay Peninsula . At this time also, teak and tea were introduced to India and breadfruit , pepper and starfruit to the Caribbean. Included in the charter of these gardens

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1380-525: 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

1495-457: A wide influence on both botany and horticulture, as plants poured into it from around the world. The garden's golden age came in the 18th century, when it became the world's most richly stocked botanical garden. Its seed-exchange programme was established in 1682 and still continues today. With the increase in maritime trade , ever more plants were being brought back to Europe as trophies from distant lands, and these were triumphantly displayed in

1610-470: A year. Historically, botanical gardens exchanged plants through the publication of seed lists (these were called Latin : Indices Seminae in the 18th century). This was a means of transferring both plants and information between botanical gardens. This system continues today, although the possibility of genetic piracy and the transmission of invasive species has received greater attention in recent times. The International Association of Botanic Gardens

1725-509: Is a conservatory housed in a Lord & Burnham greenhouse . It is divided into separate rooms, each simulating a different habitat : Except for the Hawaiian house, the galleries, and the south lobby, none of the conservatory has air conditioning . Each room is closely monitored by computer-operated sensors to maintain the environment best suited to the plants in that room. Humidity , sunlight and temperature are regulated by means of

1840-412: 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

1955-434: 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

2070-435: 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,

2185-487: 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

2300-543: 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

2415-488: Is closely linked to the history of botany itself. The botanical gardens of the 16th and 17th centuries were medicinal gardens, but the idea of a botanical garden changed to encompass displays of the beautiful, strange, new and sometimes economically important plant trophies being returned from the European colonies and other distant lands. Later, in the 18th century, they became more educational in function, demonstrating

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2530-460: 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

2645-627: 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

2760-430: 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

2875-523: Is inside the Parque La Carolina is a 165.5-acre (670,000 m ) park in the centre of the Quito central business district , bordered by the avenues Río Amazonas, de los Shyris, Naciones Unidas, Eloy Alfaro, and de la República. The botanical garden of Quito is a park, a botanical garden, an arboretum and greenhouses of 18,600 square meters that is planned to increase, maintain the plants of

2990-528: 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

3105-669: Is respected worldwide for the published work of its scientists, the education of horticultural students, its public programmes, and the scientific underpinning of its horticulture. In 1728, John Bartram founded Bartram's Garden in Philadelphia , one of the continent's first botanical gardens. The garden is now managed as a historical site that includes a few original and many modern specimens as well as extensive archives and restored historical farm buildings. The large number of plants needing description were often listed in garden catalogues; and at this time Carl Linnaeus established

3220-556: 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

3335-641: Is the dew point . The amount of water vapor needed to achieve saturation increases as 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

3450-1101: Is the acquisition and dissemination of botanical knowledge. A contemporary botanic garden is a strictly protected green area, where a managing organization creates landscaped gardens and holds documented collections of living plants and/or preserved plant accessions containing functional units of heredity of actual or potential value for purposes such as scientific research, education, public display, conservation, sustainable use, tourism and recreational activities, production of marketable plant-based products and services for improvement of human well-being. Worldwide, there are now about 1800 botanical gardens and arboreta in about 150 countries (mostly in temperate regions) of which about 550 are in Europe (150 of which are in Russia ), 200 in North America , and an increasing number in East Asia. These gardens attract about 300 million visitors

3565-450: 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

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3680-558: 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

3795-552: Is the oldest continually-operating botanic garden in the United States. The Columbian Institute for the Promotion of Arts and Sciences in Washington, DC first suggested the creation of the Botanic Garden in 1816. In 1820 it was given land by an act of Congress. The land was located west of the Capitol extending from First Street to Third Street between Pennsylvania and Maryland Avenues. The facility ceased to operate in 1837 when

3910-437: 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

4025-546: Is to maintain documented collections of living plants for the purposes of scientific research, conservation, display, and education, although this will depend on the resources available and the special interests pursued at each particular garden. The staff will normally include botanists as well as gardeners. Many botanical gardens offer diploma/certificate programs in horticulture, botany and taxonomy. There are many internship opportunities offered to aspiring horticulturists. As well as opportunities for students/researchers to use

4140-502: Is to provide inspiration and ideas for home gardeners who visit it. It displays a variety of small structured and non-structured gardens, and infuses color, shape, and planting themes. One section of the garden is certified as a National Wildlife Federation Backyard Wildlife Habitat. The Park also houses the administrative building for the United States Botanic Garden. The Production Facility in southwest D.C.

4255-589: Is used for growing and storing plants for propagation , for collection maintenance, or for display in upcoming annual shows. The USBG participates in CITES (the Convention on International Trade in Endangered Species), which means that it cares for plants seized by Customs . It specializes in orchids and succulents . There are four plants in the garden that are believed to be directly related to

4370-670: The Botanical Garden of the University of Vienna and Hortus Botanicus Leiden . Many plants were being collected from the Near East , especially bulbous plants from Turkey . Clusius laid the foundations of Dutch tulip breeding and the bulb industry, and he helped create one of the earliest formal botanical gardens of Europe at Leyden where his detailed planting lists have made it possible to recreate this garden near its original site. The hortus medicus of Leyden in 1601

4485-822: The Global Strategy for Plant Conservation by producing a range resources and publications, and by organizing international conferences and conservation programs. Communication also happens regionally. In the United States, there is the American Public Gardens Association (formerly the American Association of Botanic Gardens and Arboreta), and in Australasia there is the Botanic Gardens of Australia and New Zealand (BGANZ). The history of botanical gardens

4600-842: The Government Hill in Victoria City , Hong Kong Island . The Koishikawa Botanical Garden in Tokyo, with its origin going back to the Tokugawa shogunate 's ownership, became in 1877 part of the Tokyo Imperial University . In Sri Lanka major botanical gardens include the Royal Botanic Gardens, Peradeniya (formally established in 1843), Hakgala Botanical Gardens (1861) and Henarathgoda Botanical Garden (1876). Jardín Botánico de Quito

4715-629: 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}

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4830-1001: The Royal Tasmanian Botanical Gardens , 1818; the Royal Botanic Gardens, Melbourne , 1845; Adelaide Botanic Gardens , 1854; and Brisbane Botanic Gardens , 1855. These were established essentially as colonial gardens of economic botany and acclimatisation. The Auburn Botanical Gardens , 1977, located in Sydney's western suburbs , are one of the popular and diverse botanical gardens in the Greater Western Sydney area. Major botanical gardens in New Zealand include Dunedin Botanic Gardens , 1863; Christchurch Botanic Gardens , 1863; Ōtari-Wilton's Bush , 1926; and Wellington Botanic Gardens , 1868. Hong Kong Botanic Gardens , 1871 (renamed Hong Kong Zoological and Botanical Gardens in 1975), up from

4945-425: 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

5060-526: 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

5175-506: The "Father of Botany". There is some debate among science historians whether this garden was ordered and scientific enough to be considered "botanical", and suggest it more appropriate to attribute the earliest known botanical garden in Europe to the botanist and pharmacologist Antonius Castor , mentioned by Pliny the Elder in the 1st century. Though these ancient gardens shared some of

5290-408: The 16th and 17th centuries, the first plants were being imported to these major Western European gardens from Eastern Europe and nearby Asia (which provided many bulbs ), and these found a place in the new gardens, where they could be conveniently studied by the plant experts of the day. For example, Asian introductions were described by Carolus Clusius (1526–1609), who was director, in turn, of

5405-685: The British and Dutch, in India , South-east Asia and the Caribbean . This was also the time of Sir Joseph Banks 's botanical collections during Captain James Cook 's circumnavigations of the planet and his explorations of Oceania , which formed the last phase of plant introduction on a grand scale. There are currently about 230 tropical botanical gardens with a concentration in southern and south-eastern Asia. The first botanical garden founded in

5520-618: The Chelsea Physic Garden to the Province of Georgia in 1732 and tea into India by Calcutta Botanic Garden. The transfer of germplasm between the temperate and tropical botanical gardens was undoubtedly responsible for the range of agricultural crops currently used in several regions of the tropics. The first botanical gardens in Australia were founded early in the 19th century. The Royal Botanic Gardens, Sydney , 1816;

5635-521: The Christian conquest in 1085 CE. Ibn Bassal then founded a garden in Seville, most of its plants being collected on a botanical expedition that included Morocco, Persia, Sicily, and Egypt. The medical school of Montpelier was also founded by Spanish Arab physicians, and by 1250 CE, it included a physic garden, but the site was not given botanic garden status until 1593. Botanical gardens, in

5750-1023: The Netherlands ( Hortus Botanicus Leiden , 1590; Hortus Botanicus (Amsterdam) , 1638), Germany ( Alter Botanischer Garten Tübingen , 1535; Leipzig Botanical Garden , 1580; Botanischer Garten Jena , 1586; Botanischer Garten Heidelberg , 1593; Herrenhäuser Gärten, Hanover , 1666; Botanischer Garten der Christian-Albrechts-Universität zu Kiel , 1669; Botanical Garden in Berlin , 1672), Switzerland ( Old Botanical Garden, Zürich , 1560; Basel , 1589); England ( University of Oxford Botanic Garden , 1621; Chelsea Physic Garden , 1673); Scotland ( Royal Botanic Garden Edinburgh , 1670); and in France ( Jardin des plantes de Montpellier , 1593; Faculty of Medicine Garden, Paris, 1597; Jardin des Plantes , Paris, 1635), Denmark ( University of Copenhagen Botanical Garden , 1600); Sweden ( Uppsala University , 1655). During

5865-679: The Old Patent Office greenhouse, and were cared for there until 1850. At that time, a botanic garden was built to house the collection in front of the Capitol, where the Capitol reflecting pool is now located. Abolitionist Photius Fisk conducted scientific exploration of minerals and plants. While he was U.S. Navy chaplain on the Frigate Raritan in South America and the Pacific he collected seeds and rare plants for

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5980-743: The Royal Botanic Gardens, Kew (1759) and Orotava Acclimatization Garden (in Spanish) , Tenerife (1788) and the Real Jardín Botánico de Madrid (1755) were set up to cultivate new species returned from expeditions to the tropics; they also helped found new tropical botanical gardens. From the 1770s, following the example of the French and Spanish , amateur collectors were supplemented by official horticultural and botanical plant hunters. These botanical gardens were boosted by

6095-534: The Royal Garden set aside as a physic garden. William Aiton (1741–1793), the first curator, was taught by garden chronicler Philip Miller of the Chelsea Physic Garden whose son Charles became first curator of the original Cambridge Botanic Garden (1762). In 1759, the "Physick Garden" was planted, and by 1767, it was claimed that "the Exotick Garden is by far the richest in Europe". Gardens such as

6210-630: The Spanish invaders, not only with their appearance, but also because the indigenous Aztecs employed many more medicinal plants than did the classical world of Europe. Early medieval gardens in Islamic Spain resembled botanic gardens of the future, an example being the 11th-century Huerta del Rey garden of physician and author Ibn Wafid (999–1075 CE) in Toledo . This was later taken over by garden chronicler Ibn Bassal (fl. 1085 CE) until

6325-399: The United States Botanic Garden. Some of the species he gathered were the vanilla plant , dendrobium , cattleya , epidendrum , stanhopea , and several other named and unnamed species. Most of the flowers were from Brazil. He also obtained the rare butterfly flower Oncidium Papilio from Saint Thomas which he carefully guarded. Photius Fisk kept careful notes of his observations of

6440-486: The Vatican grounds in 1447, for a garden of medicinal plants that were used to promote the teaching of botany, and this was a forerunner to the University gardens at Padua and Pisa established in the 1540s. Certainly the founding of many early botanic gardens was instigated by members of the medical profession. In the 17th century, botanical gardens began their contribution to a deeper scientific curiosity about plants. If

6555-424: 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

6670-663: 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

6785-481: The characteristics of present-day botanical gardens, the forerunners of modern botanical gardens are generally regarded as being the medieval monastic physic gardens that originated after the decline of the Roman Empire at the time of Emperor Charlemagne (742–789 CE). These contained a hortus , a garden used mostly for vegetables, and another section set aside for specially labelled medicinal plants and this

6900-448: 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

7015-442: The classification systems being developed by botanists in the gardens' museums and herbaria. Botanical gardens had now become scientific collections, as botanists published their descriptions of the new exotic plants, and these were also recorded for posterity in detail by superb botanical illustrations. In this century, botanical gardens effectively dropped their medicinal function in favour of scientific and aesthetic priorities, and

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7130-405: The collection for their studies. The origin of modern botanical gardens is generally traced to the appointment of botany professors to the medical faculties of universities in 16th-century Renaissance Italy, which also entailed curating a medicinal garden . However, the objectives, content, and audience of today's botanic gardens more closely resembles that of the grandiose gardens of antiquity and

7245-402: The country (Ecuador is among the 17 richest countries in the world in the native species, a study on this matter). The Ecuadorian flora classified, determines the existence of 17,000 species) Humidity 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

7360-415: 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

7475-481: The educational garden of Theophrastus in the Lyceum of ancient Athens. The early concern with medicinal plants changed in the 17th century to an interest in the new plant imports from explorations outside Europe as botany gradually established its independence from medicine. In the 18th century, systems of nomenclature and classification were devised by botanists working in the herbaria and universities associated with

7590-544: The end of the 18th century, Kew, under the directorship of Sir Joseph Banks , enjoyed a golden age of plant hunting, sending out collectors to the South African Cape , Australia , Chile , China , Ceylon , Brazil , and elsewhere, and acting as "the great botanical exchange house of the British Empire ". From its earliest days to the present, Kew has in many ways exemplified botanic garden ideals, and

7705-465: 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

7820-443: 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

7935-590: 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

8050-474: 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

8165-519: The flora being sent back to Europe from various European colonies around the globe . At this time, British horticulturalists were importing many woody plants from Britain's colonies in North America , and the popularity of horticulture had increased enormously, encouraged by the horticultural and botanical collecting expeditions overseas fostered by the directorship of Sir William Jackson Hooker and his keen interest in economic botany . At

8280-418: 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

8395-434: The gardens, these systems often being displayed in the gardens as educational "order beds ". With the rapid expansion of European colonies around the globe in the late 18th century, botanic gardens were established in the tropics, and economic botany became a focus with the hub at the Royal Botanic Gardens, Kew , near London. Over the years, botanical gardens, as cultural and scientific organisations, have responded to

8510-409: 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

8625-450: 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

8740-440: 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

8855-488: The interests of botany and horticulture . Nowadays, most botanical gardens display a mix of the themes mentioned and more; having a strong connection with the general public, there is the opportunity to provide visitors with information relating to the environmental issues being faced at the start of the 21st century, especially those relating to plant conservation and sustainability . The "New Royal Horticultural Society Dictionary of Gardening" (1999) points out that among

8970-599: The latest plant classification systems devised by botanists working in the associated herbaria as they tried to order these new treasures. Then, in the 19th and 20th centuries, the trend was towards a combination of specialist and eclectic collections demonstrating many aspects of both horticulture and botany. The idea of "scientific" gardens used specifically for the study of plants dates back to antiquity. Near-eastern royal gardens set aside for economic use or display and containing at least some plants gained by special collecting trips or military campaigns abroad, are known from

9085-414: 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 ,

9200-456: 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

9315-508: The modern sense, developed from physic gardens , whose main purpose was to cultivate herbs for medical use as well as research and experimentation. Such gardens have a long history. In Europe, for example, Aristotle (384 BCE – 322 BCE) is said to have had a physic garden in the Lyceum at Athens, which was used for educational purposes and for the study of botany, and this was inherited, or possibly set up, by his pupil Theophrastus ,

9430-444: 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

9545-478: The original Wilkes Expedition . Botanical garden A botanical garden or botanic garden is a garden with a documented collection of living plants for the purpose of scientific research, conservation, display, and education. It is their mandate as a botanical garden that plants are labelled with their botanical names . It may contain specialist plant collections such as cacti and other succulent plants , herb gardens , plants from particular parts of

9660-724: The physicians (referred to in English as apothecaries ) delivered lectures on the Mediterranean "simples" or " officinals " that were being cultivated in the grounds. Student education was no doubt stimulated by the relatively recent advent of printing and the publication of the first herbals. All of these botanical gardens still exist, mostly in their original locations. The tradition of these Italian gardens passed into Spain Botanical Garden of Valencia , 1567) and Northern Europe , where similar gardens were established in

9775-399: The plants. In February 1853, he immediately traveled to Washington and gave the plants to the superintendent and botanist of the United States Botanic Garden W. D. Breckenridge. In 1933, the building was moved to its present location, just to the southwest of the Capitol, bordered by Maryland Avenue on the north, First Street on the east, Independence Avenue on the south, and Third Street on

9890-447: The private estates of the wealthy, in commercial nurseries , and in the public botanical gardens. Heated conservatories called " orangeries ", such as the one at Kew, became a feature of many botanical gardens. Industrial expansion in Europe and North America resulted in new building skills, so plants sensitive to cold were kept over winter in progressively elaborate and expensive heated conservatories and glasshouses. The 18th century

10005-557: The public for the purposes of recreation, education and research." The term tends to be used somewhat differently in different parts of the world. For example a large woodland garden with a good collection of rhododendron and other flowering tree and shrub species is very likely to present itself as a "botanical garden" if it is located in the US, but very unlikely to do so if in the UK (unless it also contains other relevant features). Very few of

10120-824: The purposes of scientific research, conservation, display and education." The following definition was produced by staff of the Liberty Hyde Bailey Hortorium of Cornell University in 1976. It covers in some detail the many functions and activities generally associated with botanical gardens: A botanical garden is a controlled and staffed institution for the maintenance of a living collection of plants under scientific management for purposes of education and research, together with such libraries, herbaria, laboratories, and museums as are essential to its particular undertakings. Each botanical garden naturally develops its own special fields of interests depending on its personnel, location, extent, available funds, and

10235-417: 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

10350-491: 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

10465-440: 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

10580-544: The rubber plant was introduced to Singapore. Especially in the tropics, the larger gardens were frequently associated with a herbarium and museum of economy. The Botanical Garden of Peradeniya had considerable influence on the development of agriculture in Ceylon where the Para rubber tree ( Hevea brasiliensis ) was introduced from Kew, which had itself imported the plant from South America . Other examples include cotton from

10695-403: 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

10810-502: 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,

10925-743: The second millennium BCE in ancient Egypt , Mesopotamia , Crete , Mexico and China . In about 2800 BCE, the Chinese Emperor Shen Nung sent collectors to distant regions searching for plants with economic or medicinal value. It has also been suggested that the Spanish colonization of Mesoamerica influenced the history of the botanical garden as gardens in Tenochtitlan established by king Nezahualcoyotl , also gardens in Chalco (altépetl) and elsewhere, greatly impressed

11040-428: The sites used for the UK's dispersed National Plant Collection , usually holding large collections of a particular taxonomic group, would call themselves "botanic gardens". This has been further reduced by Botanic Gardens Conservation International to the following definition which "encompasses the spirit of a true botanic garden": "A botanic garden is an institution holding documented collections of living plants for

11155-692: The society stopped holding meetings. However it was re-instituted in 1842 when the Wilkes expedition of the South Seas brought back a collection of plants. In 1838, Charles Wilkes set out on the United States Exploring Expedition commissioned by Congress to circumnavigate the globe and explore the Pacific Ocean. During this trip (the "Wilkes Expedition"), Wilkes collected live and dried specimens of plants and

11270-404: The system of binomial nomenclature which greatly facilitated the listing process. Names of plants were authenticated by dried plant specimens mounted on card (a hortus siccus or garden of dried plants) that were stored in buildings called herbaria , these taxonomic research institutions being frequently associated with the botanical gardens, many of which by then had "order beds" to display

11385-463: 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

11500-417: The term "botanic garden" came to be more closely associated with the herbarium, library (and later laboratories) housed there than with the living collections – on which little research was undertaken. The late 18th and early 19th centuries were marked by the establishment of tropical botanical gardens as a tool of colonial expansion (for trade and commerce and, secondarily, science) mainly by

11615-401: The terms of its charter. It may include greenhouses, test grounds, an herbarium, an arboretum, and other departments. It maintains a scientific as well as a plant-growing staff, and publication is one of its major modes of expression. This broad outline is then expanded: The botanic garden may be an independent institution, a governmental operation, or affiliated to a college or university. If

11730-847: The tropics was the Pamplemousses Botanical Garden in Mauritius , established in 1735 to provide food for ships using the port, but later trialling and distributing many plants of economic importance. This was followed by the West Indies ( Saint Vincent and the Grenadines Botanic Gardens , 1764) and in 1786 by the Acharya Jagadish Chandra Bose Botanical Garden in Calcutta , India founded during

11845-519: The various kinds of organizations known as botanical gardens, there are many that are in modern times public gardens with little scientific activity, and it cited a tighter definition published by the World Wildlife Fund and IUCN when launching the "Botanic Gardens Conservation Strategy" in 1989: "A botanic garden is a garden containing scientifically ordered and maintained collections of plants, usually documented and labelled, and open to

11960-416: 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

12075-468: 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

12190-499: 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

12305-698: The west. The building was closed for renovations on September 1, 1997, and reopened to the public on December 11, 2001. At the time of closure for renovation, plants in the collection were either placed in storage at the USBG Production Facility, retired to greenhouses in Florida , or composted. The USBG proper consists of three locations: the Conservatory , Bartholdi Park , and the Production Facility . The Conservatory

12420-696: The world, and so on; there may be glasshouses or shadehouses , again with special collections such as tropical plants , alpine plants , or other exotic plants that are not native to that region. Most are at least partly open to the public, and may offer guided tours, public programming such as workshops, courses, educational displays, art exhibitions , book rooms, open-air theatrical and musical performances, and other entertainment. Botanical gardens are often run by universities or other scientific research organizations, and often have associated herbaria and research programmes in plant taxonomy or some other aspect of botanical science. In principle, their role

12535-439: Was a perfect square divided into quarters for the four continents, but by 1720, though, it was a rambling system of beds, struggling to contain the novelties rushing in, and it became better known as the hortus academicus . His Exoticorum libri decem (1605) is an important survey of exotic plants and animals that is still consulted today. The inclusion of new plant introductions in botanic gardens meant their scientific role

12650-558: Was called the herbularis or hortus medicus —more generally known as a physic garden, and a viridarium or orchard. These gardens were probably given impetus when Charlemagne issued a capitulary , the Capitulary de Villis, which listed 73 herbs to be used in the physic gardens of his dominions. Many of these were found in British gardens even though they only occurred naturally in continental Europe, demonstrating earlier plant introduction. Pope Nicholas V set aside part of

12765-556: Was formed in 1954 as a worldwide organisation affiliated to the International Union of Biological Sciences . More recently, coordination has also been provided by Botanic Gardens Conservation International (BGCI), which has the mission "To mobilise botanic gardens and engage partners in securing plant diversity for the well-being of people and the planet". BGCI has over 700 members – mostly botanic gardens – in 118 countries, and strongly supports

12880-643: Was marked by introductions from the Cape of South Africa – including ericas , geraniums , pelargoniums , succulents, and proteaceous plants – while the Dutch trade with the Dutch East Indies resulted in a golden era for the Leiden and Amsterdam botanical gardens and a boom in the construction of conservatories. The Royal Gardens at Kew were founded in 1759, initially as part of

12995-658: Was now widening, as botany gradually asserted its independence from medicine. In the mid to late 17th century, the Paris Jardin des Plantes was a centre of interest with the greatest number of new introductions to attract the public. In England , the Chelsea Physic Garden was founded in 1673 as the "Garden of the Society of Apothecaries". The Chelsea garden had heated greenhouses , and in 1723 appointed Philip Miller (1691–1771) as head gardener . He had

13110-558: Was one of the first to use wardian cases to maintain live plants on long voyages. Wilkes returned in 1842 with a massive collection of plants previously unknown in the United States. The dried specimens comprised the core of what is now the National Herbarium , an herbarium curated by the Smithsonian Institution's National Museum of Natural History . The live specimens and seeds came to be housed in

13225-442: Was the investigation of the local flora for its economic potential to both the colonists and the local people. Many crop plants were introduced by or through these gardens – often in association with European botanical gardens such as Kew or Amsterdam – and included cloves , tea , coffee , breadfruit, cinchona , sugar , cotton , palm oil and Theobroma cacao (for chocolate). During these times,

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