Chapter 9 - Wind: small-scale and local systems Flashcards
How does mechanical turbulence differ from thermal turbulence?
Mechanical turbulence = something gets in the way of the regular flow (e.g. friction near ground)
Thermal turbulence = increase with heating of surface –> convection of hot air –> unstable atmosphere.
Why are winds near the surface typically stronger and more gusty in the afternoon?
Convection during day because of heating –> mixing with air aloft (fast moving air) –> unstable atmosphere.
What is wind shear and how does it relate to clear air turbulence?
Occur when wind changes its speed and/or direction abruptly. Clear air turbulence is wind shear with clean air.
What are necessary conditions for the development of large wind waves?
Strong wind and high obstacles.
Why do winds usually change direction and speed when moving over a large body of water?
Less friction over water –> higher speed –> increase in Coriolis force –> more deviation –> change in direction.
Which winds will most likely produce clouds: a valley breeze of a mountain breeze?
Valley breeze - because the air is rising.
Describe how dust devils usually form.
Sun heats the ground –> atmosphere aloft unstable –> convection –> air takes dust, sand, and dirt with it –> wind breeze comes and makes it spin.
Discuss the factors that contribute to the summer monsoon and the winter monsoon in India.
Winter monsoon: Land breeze
High pressure in Siberia –> clockwise circulation of air brings dry air –> clear, dry weather
Summer monsoon: Sea breeze
Low pressure continent –> counterclockwise circulation of air –> cold air ocean to hot air land –> mountains lifts air and it condensates –> humid, rain, thunderstorms.
In which part of the world would you expect each of these following winds, and what type of weather would each bring?
(a) Foehn
(b) California northern
(c) Santa Anna Wind
(d) Zonda
(e) Chinook
(f) Colombia gorge wind
(g) Sirocco
(h) Mistrel
(a) Winds along leeward side/downslope winds. Can exist everywhere.
(b) Northern half of California, brings hot weather.
(c) Southern California. Brings warm dry weather.
(d) Argentina. Brings hot air and strong winds.
(e) Rocky mountains (northern New Mexico into Canada) Brings hot air and strong winds.
(f) Colombia river gorge. Brings very cold air and strong winds down a slope.
(g) North Africa. Brings hot air with dust etc. Goes north from Sahara.
(h) Rhone valley in France. Cold air from western mountains, very cold!
Why is it dangerous during hang-gliding to enter the downwind side of the hill when the wind speed is strong?
You could die because of the Foehn-wind.
Describe how a suburb/city breeze would look like.
Day: High pressure city –> low pressure suburb
Night: Low pressure city
Which site would be best to construct a wind turbine? A, B or C? Which would be worst?
—-> (prevailing wind) |
– . –
| | |
– . – ____|____ – . –
| - - |
| - - |
____________________________________
A B C
B best because of altitude, no friction. C worst., because not trustworthy, a lot of friction!
Explain why cities near large bodies of cold water experience well-developed sea breezes, but only poor developed land breezes.
The cool water has high air pressure since the air is not rising there. And the wind always go from high pressure to low pressure. Therefore the wind will go from water to city = sea breeze.
