Chapter 7 PPT Flashcards
What are the four forces that control the movement of air
- Pressure Gradient Force
- Gravitational Force
- Frictional Force
- Coriolis Force
What can a Force be thought of doing?
A force can be thought of as a push or a pull
Pressure Gradient
The rate at which pressure changes with distance
Pressure Gradient Force
The force applied on an air parcel due to pressure differences
On a surface pressure map is the Pressure Gradient Force always perpendicular to the isobars from high to low pressure?
Yes
If vertical pressure gradient is so strong, why doesn’t the air just shoot off into space?
Gravitational force opposes the vertical PGF
Frictional Force
A drag force acting in a direction opposite the motion of the air
is frictional force strongest closest to the surface of the earth?
Yes it is
Gravitational Force
Exerts a gravitational pull on the atmosphere that is always directed down towards the center of the earth.
What three causes that create turbulence in the atmosphere?
- Mechanical force
- Thermal Turbulence
- Shear Induced Turbulence
What is Mechanical Turbulence?
Air encounters obstructions on the surface
What is Thermal Turbulence?
Heated air rises and mixes with the air above
What is Shear Induced Turbulence?
Seen when wind speed changes rapidly over a short distance
How deep is the frictional layer?
it varies from 100’s to 1000’s of meters.
Which situation would likely result in the highest atmospheric boundary layer (Largest amount of turbulence)?
High winds over boulder during a hot summer day
Coriolis Force
An apparent force due to Earths rotation
What do you call it when you have, Conservation of angular momentum, and centrifugal force?
The Coriolis Force
What direction do objects turn in the Northern hemisphere because of the Coriolis force?
Objects turn right towards the equator.
What direction do objects in the southern hemisphere because of the Coriolis force?
Objects turn left towards the equator.
Can the Coriolis force affect the direction of motion of an object?
Yes
Can the Coriolis force change the speed of objects?
No
Is the Coriolis force zero at the equator?
Yes, and increases to a maximum at the poles.
Newtons first law of Motion
An object at rest will remain at rest and an object in motion will remain in motion traveling at a constant speed in a straight line as long as their is no force exerted on the object.
Acceleration
A change in speed or direction
Newtons second law of motion?
The force exerted on an object equals its mass times its acceleration
Hydrostatic Balance?
The upward directed PGF is exactly balanced by the downward directed gravitational force.
Geostrophic Balance
The Horizontal PGF is balanced by the Coriolis Force
Does the PGF always go from high to low pressure always?
Yes, Pressure Gradient Force, always goes from high to low pressure
Geostrophic Wind?
The wind that would exist if the atmosphere were in geostrophic balance
Does the Geostrophic Wind Always go along with the Isobars?
Yes
Jetstream
A Narrow band of strong winds that encircle the earth in the mid latitudes.
