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Geol 1350: Test 3
What are the forces that influence the winds |
pressure gradient force
coriolis force
centrifugal force
frictional force |
what determines the magnitude of Coriolis Force |
V is the wind speed and f is the coriolis parameter |
what is the apparent force of CF due to |
it is due to the rotation of the earth |
For CF what does the magnitude depend on |
it depends on latitude and the speed of the air parcel |
If the latitude is the, the Coriolis force will be |
larger |
what is the Coriolis force at the equator and at the pole |
zero, maximum |
The CF causes a parcel to deflect in which direction in the northern hemisphere |
it causes the parcel to deflect right of its intended path |
The CF causes a parcel to deflect in which direction in the southern hemisphere |
it causes the parcel to deflect left of its intended path in the southern hemisphere |
what is the only thing CF can influence |
CF only influences wind direction, no effect on wind speed |
what is the equation for the magnitude of Centrifugal Force |
CENTF= mV2/R |
what does the m stand for |
mass |
what does the R stand for |
the radius of curvature of the path |
what does the V stand for |
V is the speed of the air parcel |
what is the direction of Centrifugal Force |
pointing away from the center of the curve |
If it has a faster spped and tighter curve of the path traveled (small R), what happens to the centrifugal force |
the centrifugal force is larger |
What does the frictional drag of the ground do to the wind |
The frictional drag of the ground slows wind down |
what is the equation for Frictional Force |
FF=-kV |
what is the magnitude of FF depend on |
it depends on V and K |
what does k stand for |
the roughness of the earth's surface |
what is the direction of Frictional Force |
it always acts in the direction opposite to the movement of teh air parcel (-) |
where is FF important |
in the friction layer (planetary boundary layer) |
For FF where is the lowest level for atmosphere |
1000m |
what is the Geostrophic Balance |
it is the most fundamental horizontal force balance when the pressure gradient force is counter balanced by the CF |
what is the equation for Geostrophic balance |
PGF+CF=0 |
what is the resulting wind of Geostrophic balance called |
Geostrophic Wind |
what is the Geostrophic wind good for |
it is a good approximation to winds above earth's surface |
what is the gradient wind |
it is the flow around a curved path where there are three forces involved in the balance (gradient balance) |
what are the three forces involved with the gradient balance |
pressure gradient force
CF
Centrifugal Force |
what is the equation for gradient balance |
PGF+CF+CENTF=0 |
when is the gradient balance important |
it is important near high or low pressure centers |
what are the scales of motion |
microscale
mesoscale
synoptic scale
planetary scale |
where does microscale happen |
meters to 1km |
what happens in a microscale |
turbulent eddies |
how long do eddies last |
lifetimes of minutes |
what range is the mesoscale |
1 km to 200 km |
what is contained in the mesoscale |
local winds and circulations |
what is contained in local winds and circulations |
land/sea breezes, mountain/ valley winds, thunderstorms, tornadoes |
what is the lifetime for the mesoscale |
hours to a day |
what is the range for a synoptic scale |
200 km to 2000 km |
what is contained in the synoptic scale |
hurricanes, tropical storms, lows and highs, fronts, everyday weather |
what is the lifetime for synoptic scales |
days to weeks |
what is the planetary scale |
above 2000 km |
what is contained in a planetary scale |
longwaves in westerlies |
what is the lifetime of planetary scales |
weeks |
what is the forces used for microscale |
pressure gradient force, centrifugal force, and FF are important. CF is negligible |
what are the forces used in the mesoscale |
CF becomes more important at the large end of this category |
what is the forces used in the synoptic scale |
the Geostrophic balance between pressure gradient force and CF is dominant |
what is the force for the Global-scale |
Geostrophic balance dominates |
which heats more quickly land or water |
Land which creates temperature differences along the coastline |
what creates a sea breeze |
the temperature difference that drives air to flow from the ocean towards land |
when is the temperature lower over land |
at night |
what causes the land to have a lower temperature at night
|
radiative cooling of the land surface
|
what produces a land breeze circulation
|
the pressure difference with high pressure over land
|
what does a land breeze circulation cause
|
air flowing towards ocean near the surface and return flow aloft
|
what are the primary cause of the General Circulation
|
unequal heating of the earth's surface
|
what does the unequal heating of the earth's surface cause
|
tempertaure gradients---pressure gradients- winds
|
what are the two thermal direct cells
|
Hadley and Polar
|