Post on 18-Jul-2020
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Pressure and WindsGG101, Part 1:
General context/physical geographyGlobal radiation and energy systemTemperature regimes and temperature
Part II:Focus on the dynamics/processes associated with weatherThree components:
• Moisture in the atmosphere– Clouds and precipitation
• Atmospheric motions– Winds and global circulation
• Weather systems– Mechanisms behind day to day weather
Pressure and WindsToday we will introduce:
Pressure• Nature and Properties
Pressure Gradient Force• Creates motion• Local and large scale
Coriolis Force• Earth’s rotation• Influences direction of flow
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Pressure and WindsPressure
Defined as force per unit areaUnits of Pascals (1 N/m2)In the atmosphere we measure pressure in millibars (mb)
Pressure and WindsPressure and Altitude
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Pressure and WindsPressure Gradient Force
The force produced by a change in pressure between two points atthe same “level”
IsobarsLines connecting regions of equal pressure
Pressure and WindsSea and Land Breeze
L H
H L
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Pressure and WindsSea and Land Breeze
L H
H L
Pressure and WindsCoriolis Force
An apparent force resulting from the rotation of the earth
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Pressure and WindsCoriolis Force con’t.
Without Rotation With Rotation
A
B
A
A’
B B’
Pressure and WindsCoriolis Force con’t.
Without Rotation With Rotation
A
B
A
A’
BB’
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Pressure and WindsCoriolis Force con’t:
Pressure and WindsCoriolis Force On the Earth:
CF ~ velocity*sin(latitude)CF is perpendicular to the direction of motion
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Pressure and WindsCoriolis Force and Surface Winds