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Weather systems

To get a complete picture of the weather, observations are taken and plotted onto a synoptic chart. Watch this video to find out more.


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Key points

  • A synoptic chart summarises atmospheric conditions such as temperature, precipitation and wind speed.
  • Weather maps use internationally agreed standards and symbols.
  • Isobars are lines on a weather map that join-up places of equal atmospheric pressure. The closer together isobars are, the windier it is.
  • Air masses are large bodies of air, sharing similar temperature, moisture and atmospheric pressure. Fronts occur where two different air masses meet.
  • Warm fronts happen where warm air rises over a mass of cold air. The warm air cools and expands and clouds form.
  • A cold front is the transition zone where a cold air mass replaces a warm one. The cold gradually moves beneath the warm air. It will rain heavily as the warm air is pushed upwards.
  • Occluded fronts happen at the point where a cold front overtakes a warm front or vice versa. Occluded fronts bring changeable weather.
  • Depressions are areas of low atmospheric pressure, which produce cloudy, rainy and windy weather.
  • Anticyclones are the opposite of depressions. They are areas of high atmospheric pressure where the air is sinking.

All Geography videos

Weather and climate index

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