|Fronts: A narrow transistion zone, or boundary, between disparate synoptic scale air masses whose primary discontinuity is density. Fronts are commonly associated with a moisture gradient, a pressure trough, a wind shift and/or various sensible weather phenomena. A front is a convergent boundary. It is synoptic scale along the length of the front, but mesoscale across the front itself.|
A quick look at a surface cyclone
There are four types of fronts: cold, warm, occluded and stationary.
Each front marks the transition zone between air masses.
- Cold fronts are marked by blue lines with triangles pointing
toward the warm air, indicating the direction of motion.
- slope (m) = 1/50 to 1/150
- Cold fronts usually generate strong lifting and hence ahead of the front there are usually areas of moderate to strong convection.
Precipitation is usually in the form of showers and thunderstorms.
- Warm fronts are marked by red lines with half circles penetrating
the cold air and indicating the direction of motion.
- m = 1/100 to 1/300
- Warm fronts generally force air to rise over the frontal boundary
and continuos precipitation is likely. However if the air on the
warm side of the front is unstable, thunderstorms and showers
- Stationary fronts are mrked by alternating blue lines with a
triangle and red lines with a half-circle, using the same convention as
before. There is no movement.
- Occluded fronts occur when the cold front "overtakes"
the warm front, pushing the warm air above the surface.
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