Basic Geography/Climate/Recording Weather

Recording The Weather
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.
 * 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 - 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
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
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