unit 5, exam 2 Flashcards
forces that act on atmosphere
pressure gradient
coriolis
friction
geostrophic wind
forces are balanced
upper atmosphere
pressure gradient force and Coriolis balance each other out.
wind then flows perpendicular to isobars
going counter/clockwise within perspective hemisphere
gradient wind
geostrophic flow includes centripedal that maintains parallel flow around isobars
force
push or pull on an object with a vector quantity both in magnitude and direction
forces not balanced
near the surface friction slows, reduces the coriolis and allows pressure gradient forces to dominate which causes convergence in L pressures and divergence at H pressures
one cell model
hadley cell 18th century scientist proposal for trade winds single cell of air movement assumes: no land, sun directly over equator, no rotation
wind
the movement of air in response to temperature and pressure gradients
wind is light
pressure gradient is weak
widely spaced isobars
wind is sstrong
pressure gradient steep
closely spaced isobars
large gradient
fast winds
small gradient
slow winds
pressure gradient
change in air pressure over a distance
always present vertically(large gradient) and horizontally (much smaller gradient)
pressure gradient FORCE
a response to horizontal air pressure gradients, the wind blows form high pressure to low pressure, orienting perpendicular to isobars
H-pressure system
anticyclone, brings fair weather
L-pressure system
cyclone, brings stormy weather
isobars
lines that join areas with the same air pressure
newtons first law of motion
a moving object remains in constant, straight line motion unless acted upon
coriolis force
apparent force derived to describe the coriolis effects magnitude and direction of wind
-only effects direction, not wind speed
friction
resistance that an object or medium encounters as it moves in contact with another object of medium.
molecular viscosity
the random motion of molecules composing a liquid or gas, a type of fluid friction
eddy viscosity
fluid friction that arises from eddies, large irregular motions that develop with fluids.
synergistic forcing
forces operating in the atmosphere act together in governing both wind speed and direction
three cell model
accounts for the rotation of the earth
hadley(tropics)
ferrel(mid-latitudes)
polar cell
ITCZ
intertropical convergence zone
low pressure around the equator at meeting hadley cells