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Upper Air Diagrams
• Dewpoint will be replaced with the dewpoint
depression, which is the difference between
the temperature and dewpoint.
• You will not see a negative dew point
depression.
• Pressure changes to a height in meters.
This can be seen as the thickness between
the surface and the corresponding level.
• Warmer temps = higher thickness
Lower temps = lower thickness
Stacked or Tilted Trough?
• In areas of deep low pressure or heights,
the trough axis can be analyzed at each
level of the atmosphere.
• If axis at each level is in the same general
location, then it can be thought of as
vertically stacked.
• If the axis is in a different location, it can
be classified as tilted with height.
• Why is this important?
Stacked or Tilted Trough? (cont.)
• Strong developing low pressure systems tend to
tilted with height. Why?
• 500 mb heights are influenced by the
temperature of the layer from the surface to 500
mb.
• Behind a cold front, cooler air will aide in
decreasing the vertical depth of the atmosphere
just behind the front.
• Colder air = Lower heights
• In developing low pressure, the axis at each
level with height will tilt toward cooler air.
Strengthening
- mT air rises, with cP air sinking
- Helps to move system along
Stacked or Tilted Trough? (cont.)
• Once an occlusion occurs in an area of low
pressure, cooler air is wrapped around the low.
• Temperatures are about the same around the
system.
• Occlusion = weakening of system, cold front
catches the warm front.
• Example: Slow moving system or cutoff low.
More convergence at surface compared to
divergence aloft.
Weakening
- In occlusion, warm air is located over the
cooler air.
- Low begins to fill