air pressure and winds - II Flashcards
What is coriolis force?
apparent force due to the rotation of the earth
How do you calculate coriolis force?
2 * 7.3x10^-5 radian/s * sin of latitude * wind speed
What makes coriolis force larger?
higher latitude
What is the effect of coriolis force on wind direction? (for both northern and southern hemispheres)
causes wind to move right of its intended path in the northern hemisphere
causes wind to move left of its intended path in the southern hemisphere
What is centrifugal force?
when in a rotating reference, an inward acceleration is opposed by an apparent force
What makes centrifugal force larger?
fast air parcel speed and tight curvature of wind’s path
What is frictional force?
frictional drag of the ground that slows wind down
What is geostrophic balance?
when pressure gradient force is counterbalanced by coriolis force
What is geostrophic wind?
wind that results from geostrophic balance, flows parallel to isobars
What is Buys Ballot’s law?
states that if a person stands with their back towards upper-level wind, low pressure will be on their left and high pressure will be on their right.
because of this, air must blow clockwise around high pressure centers and counterclockwise around low pressure centers.
When are geostrophic winds faster?
when pressure contour intervals are narrow
When are geostrophic winds slower?
when pressure contour intervals are wider
What is gradient wind?
flow along a curved path in which pressure gradient force, coriolis force, and centrifugal force are balanced
How does frictional force affect wind?
it decreases wind speed and thus decreases coriolis force. when pressure gradient force > coriolis force, wind blows towards low pressure centers and away from high pressure centers.
How is convergence and divergence included in low pressure centers?
air blows towards low pressure centers, causing an updraft that causes cloud formation. air diverges at the top.
