The diagram shows an example of a synoptic weather chart.
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What is a synoptic weather chart?A synoptic weather is a map that summarises atmospheric conditions over a region at a given time, and can help predict daily weather conditions and events. This involves the collation of a large volume of data from numerous weather stations in different locations , which can then be interpreted and refined into weather various weather symbols that are displayed on synoptic weather charts. Although these weather charts appear rather complicated to understand, these in fact provide visual representations on weather systems occurring and the consequential weather experienced.
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Isobars
Isobars are a component of synoptic weather charts which are the lines that join points of equal pressure (similar to contours). Pressure is measured in millibars and isobars are generally drawn at intervals of 4 millibars.
Isobars are useful for identifying cyclones/depressions and anticyclones, as well as helping indicate the direction and strength of wind.
Isobars are useful for identifying cyclones/depressions and anticyclones, as well as helping indicate the direction and strength of wind.
Cyclones/depressions (low pressure system) - isobars are close together and the numbers decrease towards the centre. They also tend to indicate strong winds. Anticyclones (high pressure system) - isobars are more widely spaced and indicate light winds. The numbers increase towards the centre. The direction of the wind tends to flow parallel to the isobars, flowing clockwise around anticyclones (high) and anticlockwise around cyclones (low) in Northern Hemisphere (see weather systems for more information). Fronts and Weather Charts |
The diagram above demonstrates the differences in isobar spacing in high and low pressure areas.
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Different fronts (see weather systems for more information) are represented by different symbols on synoptic weather charts. The semi-circles/triangles show the direction of movement of the fronts. Warm air follows a warm front, whilst cold air follows a cold front.