Wind 2 Flashcards
Wind are the ground level is ______ from the geostrophic wind at _______ because the surface of the earth creates friction thats____ it down and the force of the geostrophic wind reduces
Differs
2,000ft
Slows
In the northern hemisphere the surface wind will?
Back to around 1/3 of the geostrophic wind
And 2/3 over the sea.
Does the wind flow follow the direction of the isobars?
No. Tends to blow 10-30 degrees to the isobars depending if it’s over land or sea.
What does surface heating tend to do to the wind?
Produces turbulence which evens out the irregularities and reduces friction causing the surface wind to veer and decreases
What does surface cooling do to the wind?
It backs and decreases
What is a sea breeze?
Where the land experiences a much greater rapid rise in temperature than the sea. The heat energy is transferred to the air above which rises. Cold air moves in to replace the air rising.
What happens to the wind as a sea breeze establishes?
Windspeed increases and veers
When is a sea breeze strongest?
During a sunny day when the pressure gradient is weak. Can extend 30km in land and exceed 10kts
What is katabatic wind?
When does it occur?
Lands cools and the air in contact with does also. The Air begins to fall down mountains/hills.
At night at highlands with long gentle slopes
What is anabatic wind?
Occurs when insolation is transferred to the air. The air is heated and becomes less dense. Free air starts to move up the hill
What is valley wind?
Hills/mountains modify wind. The wind is channelled along a Valley and it speeds up due to Venturi effect
Briefly describe Fohn winds
Air forced to rise due high ground, will cool at DALR until it reaches dew point and thereafter cool at SALR. May present rain fall. Will fall Lee side at SALR unless it has no water then will fall at DALR. If no water will travel a greater vertical distance as dry air. The result is a net gain in temperature.
What are mountain waves?
Air rises to cross an obstruction and descends immediately and continues to rise and fall with gradual decreasing amplitude. Waves appear stationary but the air is moving constantly.
How is it indicated that mountain waves exist?
Presence of lenticular clouds. Roll clouds also present and indicate maximum turbulence.
What is thermal wind?
A wind that blows as a difference in temperature between adjacent atmospheric areas
