Weather station at Mildura Airport, Victoria, Australia. Mildura Airport is located in Mildura, Victoria, Australia. It is the busiest regional airport in Victoria and has twice been named Australia's Rural

Surface weather observations are the fundamental data used for safety as well as climatological reasons to forecast weather and issue warnings worldwide. Climatology (from Greek grc κλίμα klima, "region zone" and grc -λογία -logia) is the study of Climate, scientifically Weather forecasting is the application of science and technology to predict the state of the atmosphere for a future time and a given location ^[1] They can be taken manually, by a weather observer, by computer through the use of automated weather stations, or in a hybrid scheme using weather observers to augment the otherwise automated weather station. A weather station is a facility with instruments and equipment to make observations of atmospheric conditions in order to provide information to make weather forecasts The ICAO defines the International Standard Atmosphere, which is the model of the standard variation of pressure, temperature, density, and viscosity with altitude in the Earth's atmosphere, and is used to reduce a station pressure to sea level pressure. The International Civil Aviation Organization ( ICAO) an agency of the United Nations, codifies the principles and techniques of international air navigation The International Standard Atmosphere (ISA is an atmospheric model of how the Pressure, Temperature, Density, and Viscosity Pressure (symbol 'p' is the force per unit Area applied to an object in a direction perpendicular to the surface Temperature is a physical property of a system that underlies the common notions of hot and cold something that is hotter generally has the greater temperature The density of a material is defined as its Mass per unit Volume: \rho = \frac{m}{V} Different materials usually have different Viscosity is a measure of the resistance of a Fluid which is being deformed by either Shear stress or Extensional stress. Altitude is the Elevation of a point or object from a known level or datum (plural data Temperature and layers The temperature of the Earth's atmosphere varies with altitude the mathematical relationship between temperature and altitude varies among five Airport observations can be transmitted worldwide through the use of the METAR observing code. METAR (METeorological Aviation Report is a format for reporting Weather information Personal weather stations taking automated observations can transmit their data to the United States mesonet through the use of the Citizens weather observer program, or internationally through the Weather Underground web site. The United States of America —commonly referred to as the The Citizen Weather Observer Program ( CWOP) allows users with computerized Weather stations to send their information via a Website to be included into the Weather Underground is a commercial weather service that provides real-time weather information via the Internet. ^[2] A thirty-year average of a location's weather observations is traditionally used to determine the station's climate. Climate encompasses the temperatures humidity rainfall atmospheric particle count and numerous other meteorogical factors in a given region over long periods of ^[3]

Airports

ASOS sensors, located at Salinas, CA

Surface weather observations have traditionally been taken at airports due to safety concerns during takeoffs and landings. An airport is a location where Aircraft such as airplanes, Helicopters and blimps take off and land The ICAO defines the International Standard Atmosphere (also known as ICAO Standard Atmosphere), which is the model of the standard variation of pressure, temperature, density, and viscosity with altitude in the Earth's atmosphere. The International Civil Aviation Organization ( ICAO) an agency of the United Nations, codifies the principles and techniques of international air navigation The International Standard Atmosphere (ISA is an atmospheric model of how the Pressure, Temperature, Density, and Viscosity The International Civil Aviation Organization (ICAO Standard Atmosphere gives the average values for meteorological element at 40°N from mean sea level (MSL to 80km (262500 ft Pressure (symbol 'p' is the force per unit Area applied to an object in a direction perpendicular to the surface Temperature is a physical property of a system that underlies the common notions of hot and cold something that is hotter generally has the greater temperature The density of a material is defined as its Mass per unit Volume: \rho = \frac{m}{V} Different materials usually have different Viscosity is a measure of the resistance of a Fluid which is being deformed by either Shear stress or Extensional stress. Altitude is the Elevation of a point or object from a known level or datum (plural data Temperature and layers The temperature of the Earth's atmosphere varies with altitude the mathematical relationship between temperature and altitude varies among five This is useful in calibrating instruments and designing aircraft,^[4] and is used to reduce a station's pressure to sea level pressure where it can then be used on weather maps. A weather map is a tool used to display information quickly showing the analysis of various meteorological quantities at various levels of the atmosphere ^[5]

In the United States, the FAA mandates the taking of weather observations for safety reasons. The Federal Aviation Administration ( FAA) is an agency of the United States Department of Transportation with authority to regulate and oversee all aspects of To help facilitate the purchase of an automated weather observing system, such as ASOS, the FAA allows federal dollars to be used for the installation of certified weather stations at airports. Automated airport weather stations are automated sensor suites which are designed to serve Aviation and meteorological observing needs for safe and efficient ^[6] The airport observations are then transmitted worldwide using the METAR observing code. METAR (METeorological Aviation Report is a format for reporting Weather information METAR reports typically come from airports or permanent weather observation stations. An airport is a location where Aircraft such as airplanes, Helicopters and blimps take off and land Reports are generated once an hour; however, if conditions change significantly, they may be updated in special reports called SPECI's. ^[7]

Data Reported

Surface weather observations can include the following elements:

• The Station Identifier, or Location identifier, consists of four characters for METAR observations,^[8] with the first representing the region of the world the station lies within. A location identifier is a symbolic representation for the name and the location of an Airport, navigation aid, or Weather station, and is used for manned For example, the first letter for areas in and around the Pacific ocean is P, and for Europe is E. The second character may represent the country/state the location lies within. For Hawaii, the first two letters are "PH" while for Great Britain, the first two letters of the station identifie are "EG". Canada and the contiguous United States are an exception, with the first letters C and K representing the regions, respectively. The final two or three letters normally represent the name of the location or airport.
• Visibility, measured in meters for most sites worldwide, except in the United States where statute miles are reported. In Meteorology, visibility is a measure of the Distance at which an object or light can be clearly discerned The metre or meter is a unit of Length. It is the basic unit of Length in the Metric system and in the International ^[9]

• Runway visibility, measured in meters in many locations worldwide, or feet within the United States. Runway Visual Range (RVR is a term used in Aviation Meteorology to define the distance over which a pilot of an aircraft on the centreline of the runway can see the The metre or meter is a unit of Length. It is the basic unit of Length in the Metric system and in the International ^[9]

• Temperature is a measure of the kinetic energy of a sample of matter. Temperature is a physical property of a system that underlies the common notions of hot and cold something that is hotter generally has the greater temperature The kinetic energy of an object is the extra Energy which it possesses due to its motion Temperature is the unique physical property that determines the direction of heat flow between two objects placed in thermal contact. If no heat flow occurs, the two objects have the same temperature;^[10] otherwise heat flows from the hotter object to the colder object. Temperature, within meteorology, is measured with thermometers exposed to the air but sheltered from direct solar exposure. Meteorology (from Greek grc μετέωρος metéōros, "high in the sky" and grc -λογία -logia) is the Interdisciplinary The thermometer is a device that measures Temperature or Temperature gradient using a variety of different principles it comes from the Greek roots ^[11] In most of the world, the degree Celsius scale is used for most temperature measuring purposes. The Celsius Temperature scale was previously known as the centigrade scale. However, the United States is the last major country in which the degree Fahrenheit temperature scale is used by most lay people, industry, popular meteorology, and government. Fahrenheit is a temperature scale named after Daniel Gabriel Fahrenheit (1686–1736 a German Physicist who proposed it in 1724 Meteorology (from Greek grc μετέωρος metéōros, "high in the sky" and grc -λογία -logia) is the Interdisciplinary ^[9] Despite this, METAR reports from the United States also report the temperature (and dewpoint, see below) in degrees Celsius.

• Dew Point is the temperature to which a given parcel of air must be cooled, at constant barometric pressure, for water vapor to condense into water. The dew point (sometimes spelled dewpoint) is the Temperature to which a given parcel of Air must be cooled at constant Barometric pressure, Temperature is a physical property of a system that underlies the common notions of hot and cold something that is hotter generally has the greater temperature Temperature and layers The temperature of the Earth's atmosphere varies with altitude the mathematical relationship between temperature and altitude varies among five General properties of water vapor Evaporation/sublimation Whenever a water molecule leaves a surface it is said to have evaporated Condensation is the change of the physical state of aggregation (or simply state of matter from gaseous phase into liquid phase The condensed water is called dew. Formation Water will condense into droplets depending on the temperature The dew point is a saturation point. When the dew point temperature falls below freezing it is called the frost point, as the water vapor no longer creates dew but instead creates frost or hoarfrost by deposition. Frost is the solid deposition of Water vapor from saturated air Frost is the solid deposition of Water vapor from saturated air Deposition is a process in which gas transforms into solid (also known as desublimation ^[12] The dew point is associated with relative humidity. Humidity is the amount of water vapor in the air In daily language the term "humidity" is normally taken to mean Relative humidity. A high relative humidity indicates that the dew point is closer to the current air temperature. Relative humidity is a measurement of the amount of Water vapor that exists in a gaseous mixture of air and water If the relative humidity is 100%, the dew point is equal to the current temperature. Given a constant dew point, an increase in temperature will lead to a decrease in relative humidity. At a given barometric pressure, independent of temperature, the dew point determines the specific humidity of the air. Humidity is the amount of water vapor in the air In daily language the term "humidity" is normally taken to mean Relative humidity. The dew point is an important statistic for general aviation pilots, as it is used to calculate the likelihood of carburetor icing and fog. General aviation (abbr GA) is one of two categories of Civil aviation. Carburetor (or carburettor) icing is an Icing condition which can affect any Carburetor under certain atmospheric conditions Fog is a cloud that is in contact with the ground Stratus clouds are usually the only clouds that touch the ground When used with the air temperature, a formula can be used to estimate the height of cumuliform, or convective, clouds. ^[13]
• Wind speed and direction is determined using anemometers located a standard 10 metres (33 ft) above ground level. Wind is the flow of Air or other Gases that compose an Atmosphere (including but not limited to the Earth's) An anemometer is a device for measuring wind speed and is one instrument used in a Weather station. Average wind speed is measured using a two-minute average in the United States,^[14] and a 10 minute average elsewhere. ^[15] Wind direction is measured using degrees, with north representing 0 or 360 degrees, with values increasing from 0 clockwise from north. Wind gusts are reported when there is variation of the wind speed of more than 10 knots (5. 1 m/s) between peaks and lulls during the sampling period. ^[14]
• Sea level pressure is the pressure at sea level or (when measured at a given elevation on land) the station pressure reduced to sea level assuming an isothermal layer at the station temperature. This is the pressure normally given in weather reports on radio, television, and newspapers or on the Internet. When barometers in the home are set to match the local weather reports, they measure pressure reduced to sea level, not the actual local atmospheric pressure. The reduction to sea level means that the normal range of fluctuations in pressure is the same for everyone. The pressures which are considered high pressure or low pressure do not depend on geographical location. This makes isobars on a weather map meaningful and useful tools. ^[16]
• Altimeter setting is a term and quantity used in aviation. An altimeter is an instrument used to measure the Altitude of an object above a fixed level Aviation refers to activities involving man-made flying devices ( Aircraft) including the people organizations and regulatory bodies involved with them The regional or local air pressure at mean sea level is called the altimeter setting, and the pressure which will calibrate the altimeter to show the height above ground at a given airfield. An airport is a location where Aircraft such as airplanes, Helicopters and blimps take off and land ^[17]
• Present weather, which present restrictions to visibility or presence of thunder or squalls, are reported in observations to indicate to aviation any possible threats during landings and takeoffs from airports. Thunder is the sound made by Lightning. Depending on the nature of the lightning and distance of the listener it can range from a sharp A squall is a sudden sharp increase in wind speed which is usually associated with active weather such as rain showers thunderstorms or heavy snow Types included in surface weather observations include precipitation, obscurations, other weather phenomena such as, well-developed dust/sand whirls, squalls, tornadic activity, sandstorms, volcanic ash, and duststorms. Volcanic ash consists of small Tephra, which are bits of pulverized rock and glass created by volcanic eruptions less than in diameter ^[18]
• Intensity of precipitation is primarily measured for meteorological concerns. However, it can be of concern to aviation as heavy precipitation can limit visibility. Also, intensity of freezing rain can determine how hazardous it is for pilots to fly nearby certain locations since it can be an in-flight hazard by depositing ice on the wings of aircraft, which can be detrimental to flight. ^[19]
• Precipitation amount over the past 6 or 24 hours is of particular interest to meteorologists in verifying forecast amounts of precipitation and determining station climatologies. Meteorology (from Greek grc μετέωρος metéōros, "high in the sky" and grc -λογία -logia) is the Interdisciplinary
• Snowfall amount during the past 6 hours is taken for meteorological and climatological concerns. "Snowfall" redirects here For other uses see Snow (disambiguation or Snowfall (disambiguation.
• Snow depth is measured for meteorological and climatological concerns once a day. However, during periods of snowfall, it is measured each six hours to determine amount of recent snowfall. ^[20]

Example of a METAR surface weather observation

METAR LBBG 041600Z 12003MPS 310V290 1400 R04/P1500N R22/P1500U +SN BKN022 OVC050 M04/M07 Q1020 NOSIG 9949//91=^[21]

Personal weather stations, maintained by citizens rather than government officials, do not use METAR code. Software allows information to be transmitted to various sites, such as Weather Underground globally,^[2] or CWOP within the United States,^[22] which can then be used by the appropriate meteorological organizations either to diagnose real-time conditions, or be used within weather forecast models. The Citizen Weather Observer Program ( CWOP) allows users with computerized Weather stations to send their information via a Website to be included into the The United States of America —commonly referred to as the

Use on weather maps

Station model used on surface weather maps

Main articles: Weather maps and Station model

Data collected by land locations coding in METAR are conveyed worldwide via phone lines or wireless technology. A weather map is a tool used to display information quickly showing the analysis of various meteorological quantities at various levels of the atmosphere A station model is a symbolic illustration showing the Weather occurring at a given reporting station. Within many nations' meteorological organizations, this data is then plotted onto a weather map using the station model. A station model is a symbolic illustration showing the Weather occurring at a given reporting station. A station model is a symbolic illustration showing the weather occurring at a given reporting station. The weather is a set of all the phenomena occurring in a given Atmosphere at a given Time. A weather station is a facility with instruments and equipment to make observations of atmospheric conditions in order to provide information to make weather forecasts ^[23] Meteorologists created the station model to plot a number of weather elements in a small space on weather maps. A weather map is a tool used to display information quickly showing the analysis of various meteorological quantities at various levels of the atmosphere ^[24] Maps filled with dense station-model plots can be difficult to read, but they allow meteorologists, pilots, and mariners to see important weather patterns.

Weather maps are used to display information quickly showing the analysis of various meteorological quantities at various levels of the atmosphere, in this case the surface layer. ^[25] Maps containing station models aid in the drawing of isotherms, which more readily identifies temperature gradients,^[26] and can help in the location of weather fronts. A weather front is a boundary separating two masses of air of different densities, and is the principal cause of meteorological phenomena. Two-dimensional streamlines based on wind speeds show areas of convergence and divergence in the wind field, which are helpful in determining the location of features within the wind pattern. Fluid flow is described in general by a Vector field in three (for steady flows or four (for non-steady flows including time dimensions A popular type of surface weather map is the surface weather analysis, which plots isobars to depict areas of high pressure and low pressure. A surface weather analysis is a special type of Weather map that provides a view of Weather elements over a geographical area at a specified time based on information High pressure Science and Engineering is studying the effects of high pressure on materials and the design and construction of devices such as a Diamond anvil A low pressure area, or " low " is a region where the Atmospheric pressure is lower in relation to the surrounding area

Ship and buoy reports

Different shapes and sizes of buoys

For over a century, reports from the world's oceans have been received real-time for safety reasons and to help with general weather forecasting. The reports are coded using the synoptic code, and relayed via radio or satellite to weather organizations worldwide. SYNOP ( surface synoptic observations) is a numerical Code (called FM-12 by WMO) used for reporting Weather observations made by manned and automated Radio is the transmission of signals by Modulation of electromagnetic waves with frequencies below those of visible Light. This article is about artificial satellites For natural satellites also known as moons see Natural satellite. ^[27] Buoy reports are automated, and maintained by the country that moored the buoy in that location. Larger moored buoys are used near shore, while smaller drifting buoys are used farther out at sea. ^[28]

Due to the importance of reports from the surface of the ocean, the voluntary observing ship program, known as VOS, was set up to train crews how to take weather observations while at sea and also to calibrate weather sensors used aboard ships when they arrive in port, such as barometers and thermometers. Due to the importance of Surface weather observations from the surface of the ocean the Voluntary observing ship program, known as VOS was set up to train crews how History The first barometer is thought to have been built unintentionally by Gasparo Berti, sometime between 1640 and 1643 The thermometer is a device that measures Temperature or Temperature gradient using a variety of different principles it comes from the Greek roots ^[29] The beaufort scale is still generally used to determine wind speed from manual observers out at sea. The Beaufort scale (ˈboʊfət is an Empirical measure for describing Wind speed based mainly on observed sea conditions Ships with anemometers have issues with determining wind speeds at higher wind speeds due to blockage of the instruments by increasing high seas. An anemometer is a device for measuring wind speed and is one instrument used in a Weather station.

Use in establishing climate of a location

Main article: Climate

Climate, (from Ancient Greek klima) is commonly defined as the weather averaged over a long period of time. Climate encompasses the temperatures humidity rainfall atmospheric particle count and numerous other meteorogical factors in a given region over long periods of The Ancient Greek language is the historical stage in the development of the Hellenic language family spanning the Archaic (c ^[30] The standard averaging period is 30 years for an individual location,^[3] but other periods may be used. Climate includes statistics other than the average, such as the magnitudes of day-to-day or year-to-year variations. The Intergovernmental Panel on Climate Change (IPCC) glossary definition is:

Climate in a narrow sense is usually defined as the “average weather”, or more rigorously, as the statistical description in terms of the mean and variability of relevant quantities over a period of time ranging from months to thousands or millions of years. The classical period is 30 years, as defined by the World Meteorological Organization (WMO). These quantities are most often surface variables such as temperature, precipitation, and wind. Climate in a wider sense is the state, including a statistical description, of the climate system. ^[31]

The main difference between climate and everyday weather is best summarized by the popular phrase "Climate is what you expect, weather is what you get. "^[32] Over historic time spans there are a number of static variables that determine climate, including: latitude, altitude, proportion of land to water, and proximity to oceans and mountains. History is the study of the past particularly the written record Those who study history as a Profession are called Historians Etymology Degree of vegetation coverage affects solar heat absorption, water retention, and rainfall on a regional level. Rain is Liquid precipitation. On Earth it is the condensation of atmospheric Water vapor into drops heavy enough to fall often making it to

References