C10 - Low Level Winds Flashcards
Define Wind?
Sustained horizontal movement of Air.
Define Wind Velocity?
Wind Speed and Direction.
Wind Direction is given using ‘____’ North and indicates the direction ‘____’ which the Wind blows (2)?
- True.
- From.
What is a Westerly Wind?
Wind coming from W/270°.
What direction does the Wind change if it is said to be Backing?
Anti-clockwise.
What direction does the Wind change if it is said to be Veering?
Clockwise.
Approximately 1 mps (metre per second) is equal to what in Knot?
2 kt.
A sudden increase in Wind Speed, often with a change in direction, lasting only a few seconds. What am I?
Gust.
A sudden increase in Wind Speed, often with a change in direction, lasting for some minutes. What am I?
Squall.
A ‘____’ is a sudden decrease in Wind Speed?
Lull.
A straight line from a circle shows what on Weather Charts?
Where this wind is blowing to.
On a Weather Charts, if the Wind Velocity Line has a feather point out, how much does this represent?
10 kt.
On a Weather Charts, if the Wind Velocity Line has a black triangle, how much does this represent?
50 kt.
On a Weather Charts, if the Wind Velocity Line has a small feather point out, how much does this represent?
5 kt.
On a Weather Charts, if the Wind Velocity Line has a small feather, 2 feather lines and a black triangle, how much does this represent?
75 kt.
Surface wind is defined as the Wind Velocity at ‘____’ Above Ground Level?
33 ft.
What is the maximum speed of a Wind Sock?
20 kt.
The ‘____’ is the force that acts from areas of High-Pressure towards areas of Low-Pressure?
Pressure Gradient Force.
Closely spaced Isobars indicate a ‘____’ Pressure Gradient Force and thus ‘____’ (2)?
- Large.
- Strong Winds.
Widely spaced Isobars indicate a ‘____’ Pressure Gradient Force and thus ‘____’ (2)?
- Weak.
- Light Wings.
‘____’ is an effect caused by the rotation of the Earth?
Coriolis.
Coriolis Force acts at ‘____’ to the ‘____’ of the Wind in the Northern Hemisphere (2)?
- 90°.
- Right.
Coriolis Force acts at ‘____’ to the ‘____’ of the Wind in the Southern Hemisphere (2)?
- 90°.
- Left.
True or False. The Coriolis Force is greatest to the Equator and zero to the Poles?
False. Greatest at Poles.
Coriolis Force is ‘____’ to Wind Speed?
Proportional.
Name two assumptions of the Geostrophic Wind Model?
- Wind blows above the Friction Layer.
- Wind blows parallel to straight Isobars.
Name two forces that are part of the Geostrophic Wind Model?
- Pressure Gradient Force.
- Coriolis Force.
For a particular Pressure Gradient Force, the Geostrophic Wind Speed increases as Latitude ‘____’?
Decreases.
What is Buys Ballot’s Law for Surface Winds in both Hemispheres (2)?
- Northern Hemisphere, with your back to the Wind, the Low Pressure is to your Left.
- Southern Hemisphere, with your back to the Wind, the Low Pressure is to your Right.
What is the difference between Gradient Wind and Geostrophic Wind?
Gradient Wind takes into account the turning of Air Flow.
Name two assumptions of the Gradient Wind Model?
- Wind blows above the Friction Layer.
- Wind blows along curved Isobars.
Name three forces that are part of the Gradient Wind Model?
- Pressure Gradient Force.
- Coriolis Force.
- Centrifugal Force.
True or False. The Centrifugal Force will increase the Pressure Gradient Force, thus increasing the Wind Speed around a High Pressure System?
True.
True or False. The Centrifugal Force will decrease the Pressure Gradient Force, thus decreasing the Speed around a Low Pressure System?
True.
For a particular Pressure Gradient Force, the Surface Wind Speed increases as Latitude ‘____’?
Decreases.
Name three forces that are part of the Surface Wind Model?
- Pressure Gradient Force.
- Coriolis Force.
- Friction Force.
For a particular Pressure Gradient Force, the Surface Wind Speed increases as Latitude ‘____’?
Decreases.
In the Northern Hemisphere, as you climb from the surface to about 2,000 ft. the Wind Direction ‘____’ and ‘____’ in Speed. When descending towards the surface, the Wind ‘____’ and ‘____’ in Speed (4)?
- Veers.
- Increases.
- Backs.
- Decreases.
On Land, the Surface Wind will decrease by ‘____’ in Speed and deviate by ‘____’ (2)?
- 50%.
- 30°.
In the Northern Hemisphere, the Surface Wind ‘____’ and ‘____’ during the day and ‘____’ and ‘____’ during the night (4)?
- Increases.
- Veers.
- Decreases.
- Backs.
True or False. The Surface Wind is stronger from 1500 than 0600?
False. Stronger at 0600.
What is a Sea Breeze?
Wind from the Sea to the Land during the Day.
True or False. Sea Breeze will be cooled and start to sink over Land?
False. It will be heated and start to rise.
What time during the Day will Sea Breeze be at its maximum?
1500.
Sea Breezes are ‘____’ Winds that blow ‘____’ Air from the Sea to the Land (2)?
- Onshore.
- Cooler.
What is a Land Breeze?
Wind from the Land to the Sea during the Night.
True or False. Land Breeze will be heated and start to rise over the Sea?
True.
What time during the Day will Night Breeze be at its maximum?
Just after Sunrise.
Land Breezes are ‘____’ Winds that only occur at Night?
Offshore.
Name three types of Mountain Winds?
- Anabatic Winds.
- Katabatic Winds.
- Foehn Winds.
What direction does Anabatic Winds move and how are they formed (2)?
- Up Sloping Terrain.
- Daytime Heating of the Mountain Slopes.
Air in contact with the Slopes of the Mountain are warmed by?
Conduction.
What is the difference between Anabatic and Valley Winds (2)?
- Anabatic Winds are warm, less dense air which flows up the slope.
- Valley Winds are cooler and sink to the bottom of the Valley.
What direction does Katabatic Winds move and how are they formed (2)?
- Down Sloping Terrain.
- Night Time cooling of the Mountain Slopes.
If the cooler air at Night from Katabatic Winds fall below the Dew Point, what weather phenomenon can occur?
Valley Fog.
Define how Antarctica Katabatic Winds are formed and their speed (2)?
- Deflected by Coriolis Force to form the Polar Easterlies.
- 100 kt.
Name three local Katabatic European winds and their location?
- Mistral Winds = South Eastern France.
- Tramontara Winds = Over the Pyrenees.
- Bora Winds = East of Adriatic.
Define Foehn Winds?
Local warm, dry wind which blows on the leeward side of a Mountain.
With Foehn Winds, expect Cloud and Rain on the ‘____’ side and warm, dry clear skies on the ‘____’ side of the Mountain (2)?
- Upwind Side.
- Downwind Side.
During Foehn Wind, what type of Stability is the Air?
Stable.
The moist air rises at the rate of ‘____’ and descents to warm air at the rate of ‘____’ (2)?
- Saturated Adiabatic Lapse Rate.
- Dry Adiabatic Lapse Rate.
