wind Flashcards
how does Coriolis force affect the pgf
- deflects motion to right in the N.H. and the left in the S.H.
- acts at right angle to the objects motion
- changes direction but not speed
true or false
geostrophic wind is when the Coriolis forces perfectly balances the PGF
True. therefore closer isobars = stronger PGF= stronger CF
what is the Coriolis parameter
Coriolis parameter f = 2Ω sinφ
what is the formula for PGF per unit mass
Δp / (ρd)
Pressure difference Δp over horizontal distance
formula of Coriolis force
2ΩV sinφ
why do we get no/ little hurricane within the 10° of the equator
Coriolis force is too small, sinφ = 0.
you need a large cf to spin up a hurricane
which three forces are involved in the wind near the surface
- pgf
- cf
- frictional force
why is warm air associated with high pressure system
in a high pressure system, the air at the surface is replaced by the air aloft. as the air is dragged from above, it warms and becomes less dense. this doesn’t form clouds
why don’t we measure wind speed close tot the ground
it is affected by friction, not accurate
1 knot =______mph
1.15
what are the requirement for the exposure of anemometer?
- standard 10m height (no friction)
- no obstructions for at least 300m
how is sonic anemometers used?
-Ultrasonic pulses are sent backwards and forwards between pairs of
transducers. -Difference in travel time for pulses travelling in opposite
directions gives component of wind vector in that direction
-speed of sound an used to measure temp.
explain briefly how rawinsondes are used to find wind speed
- radiosonde (balloon) is used.
- wind speed, direction it flows through the layers can be calculated from its motion
- radar and GPS is inspired to track
how is wind measured by satellite
scatterometer- strength of the microwaves reflected back from the sea surface depends on the roughness of the sea, which depends on the wind speed
1 knot = _____ ms^-1
0.51
