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Basic Geography/Climate/Recording Weather

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Recording The Weather

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Weather conditions are measured at weather stations. These stations contain a variety of instruments to record weather data.

The most important instruments of a weather station are:

  • Hydrometer - Are a special type of thermometer that measures the humidity by calculating the water vapour in the air.
Standard Rain Gauge
  • Rain Gauge - This is a container that collects precipitation and measured it in millimeters (mm).
  • Barometer - These instruments measures the air pressure. They may be either mercury or aneroid (vacuum) barometers. Often they are attached to a pen that charts movements in pressure on a piece of paper. The resulting chart is called a barograph.
sunshine recorder
  • Sunshine Recorder - The recorder is a chart which has the sun's rays focused onto it using a magnifying glass so it burns a record of the hours the sun shone.
  • Maximum and minimum thermometers measure the highest and lowest temperature in degrees Celsius.
  • Wind Vanes show the direction of the wind.
  • Anemometers are used to measure wind speeds, usually in km/h. The wind is caught in small cups and the speed is calculated by measuring how fast the cups rotate.

Clouds

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Recording cloud type and cloud-cover is done manually, using the naked eye. Meteorologists measure cloud-cover in eighths of the sky or oktas.

  • 0 oktas = a completely cloudless sky
  • 4 oktas = half the sky is covered in clouds
  • 8 oktas = the sky is fully clouded-over

Mapping weather

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The internationally agreed way in which to map the weather is by using synoptic charts. Data is collected across a large area from weather stations, balloons, ships, aeroplanes, and satellites. Informations on a synoptic chart is updated at least every six hours. The following information is displayed on a synoptic chart:

  • temperature
  • precipitation
  • atmospheric pressure
  • wind speed
  • direction
  • cloud coverage