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Unformatted text preview: an area of
low pressure. Low pressure readings
are usually associated with storm
systems. Tornadoes and hurricanes
can produce very low barometric
readings. Air Movement and Flow 6-1
• Fluids (air and water) flow from areas of
high pressure to areas of low pressure.
• Change in pressure across a horizontal
distance is a pressure gradient.
• Greater the difference in pressure and the shorter the
distance between them, the steeper the pressure
gradient and the stronger the wind. • Movement of air across a pressure gradient
parallel to Earth’s surface is called a wind
and winds are named for the direction from
which they come. Isobars in millibars, the closer the isobar the
stronger the winds Rain Low Pressure
High Pressure The Atmosphere in Motion • Atmospheric pressure is a measure of the force
pressing down on the Earth’s surface from the
• Pressure is often measured in different units including:
– atmospheres (1 atmosphere is the average atmospheric
pressure at sea level),
– millibars (1 atmosphere = 1013.25 millibars),
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This document was uploaded on 03/13/2014 for the course GEOS 114 at NJ City.
- Spring '10