| Pressure charts show the strength of high and low pressure areas
(often marked with a H or L) and plot the lines of equal pressure.
It's simplest to think of a pressure chart as similar to a
geographical map, with highs like mountains and lows like valleys -
The lines of equal pressure (isobars) on a pressure map are equivalent
to the lines of equal altitude (height contours) on a geographical
map.
The two important relationships between isobars and winds are -
- The wind blows almost parallel to the isobars.
- The closer the isobars, the stronger the wind and the bigger the
waves being generated.
The red semicircles indicate a warm front, which is the leading
edge of a low pressure (warm air is advancing to replace cold air).
The blue triangles indicate a cold front, which is the trailing
edge (cold air is advancing to replace warm air)..
You'll also see lines that have both triangles and semicircles.
These are "occluded" fronts, where the cold front has combined with
the warm front. |
