Weather data in remote areas is collected by automated weather stations. Equipped with a wide range of instruments and computers, the stations record and transmit information via satellite every hour. Individual observers with a small number of simple instruments also play an important part in all levels of weather forecasting.
A weather station is a facility, either on land or sea, with instruments and equipment for measuring atmospheric conditions to provide information for weather forecasts and to study the weather and climate. The measurements taken include temperature, atmospheric pressure, humidity, wind speed, wind direction, and precipitation amounts. Wind measurements are taken with as few other obstructions as possible, while temperature and humidity measurements are kept free from direct solar radiation, or insolation. Manual observations are taken at least once daily, while automated measurements are taken at least once an hour. Weather conditions out at sea are taken by ships and buoys, which measure slightly different meteorological quantities such as sea surface temperature (SST), wave height, and wave period. Drifting weather buoys outnumber their moored versions by a significant amount.
Typical weather stations have the following instruments:
- Thermometer for measuring air and sea surface temperature
- Barometer for measuring atmospheric pressure
- Hygrometer for measuring humidity
- Anemometer for measuring wind speed
- Pyranometer for measuring solar radiation
- Rain gauge for measuring liquid precipitation over a set period of time.
- Wind sock for measuring general wind speed and wind direction
- Wind vane, also called a weather vane or a weathercock: it shows whence the wind is blowing.
In addition, at certain automated airport weather stations, additional instruments may be employed, including:
- Present Weather/Precipitation Identification Sensor for identifying falling precipitation
- Disdrometer for measuring drop size distribution
- Transmissometer for measuring visibility
- Ceilometer for measuring cloud ceiling
More sophisticated stations may also measure the ultraviolet index, leaf wetness, soil moisture, soil temperature, water temperature in ponds, lakes, creeks, or rivers, and occasionally other data.
Exposure
Except for those instruments requiring direct exposure to the elements (anemometer, rain gauge), the instruments should be sheltered in a vented box, usually a Stevenson screen, to keep direct sunlight off the thermometer and wind off the hygrometer. The instrumentation may be specialized to allow for periodic recording otherwise significant manual labour is required for record keeping. Automatic transmission of data, in a format such as METAR, is also desirable as many weather station’s data is required for weather forecasting.
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