Pressure Gradient Force/ Wind balance
Wind flows from what pressure to what pressure?
High pressure to low pressure.
Which column of air is taller, warm or cold?
Warm.
How is a warm cloud characterized?
A cloud that is completely above the freezing level.
Troughs have areas of ___ height while ridges have areas of ____ height.
Low, high.
True or False: The closer together isobars are the stronger the winds between them.
True.
True or False: PGF winds flow perpendicular to isobars (lines of constant pressure.
True.
If the columns of air for 2 areas are equal, is there any air transfer between the 2?
No. Equal pressure = no wind.
How is a cold cloud characterized?
A cloud that exists all or partly above the freezing level.
(500mb) Troughs create areas of ___ temperature while ridges create areas of ____ temperature.
Low, high.
Why doesn't wind flow directly from pressure systems?
The Coriolis Force.
By keeping the change in pressure constant but decreasing the distance, PGF increases or decreases?
PGF increases.
What is the air pressure at mid levels for a warm column of air?
High.
When freezing rain falls and freezes on the surface, what process occurred here?
Accretion. Ice crystals collide with super cooled droplets. Being supersaturated (RH>100%), this precipitation freezes on contact with a surface.
Which pressure feature typically has a lower 500mb height, a trough or ridge?
Trough.
Sleet requires what type of warm layer?
Shallow warm layer for partial melting, deep cold layer to allow time to re freeze.
Change in pressure over change in distance is always multiplied by what?
-1/rowe (density)
What is the mid level pressure for a cold column of air?
Low.
What process occurs for sleet to fall?
Fracturing. Falling ice particles collide and fracture into smaller pieces.
Identify on this map where the ridge is located and where the trough is located.
Trough: Eastern U.S.
Ridge: Western U.S.
What are the three main forces that act on air?
1. Pressure Gradient Force.
2. Coriolis Force.
3. Frictional Force.
PGF Sign Problem
O=990mb
O=1000mb A O=1020mb
O=1010mb
dp/dx= 1020-1000= +
dp/dy= 990-1010= -
Explain the airflow process between these two air columns.
What process assists in the creation of snowflakes?
Aggregation. Falling crystals collide and stick together to other crystals.
Having a trough and ridge close together creates a strong or weak PGF?
Strong.
Freezing rain requires what kind of warm layer?
Deep warm layer to allow for complete melting, shallow cold layer to create supercooled droplets.