Visibility & Wind

Question 1

A ceiling is defined as the height of the

Answer 1

lowest layer of clouds or obscuring phenomena aloft that is reported as broken or overcast

Question 2

You can expect to see an operating rotating beacon at an airport during daylight hours when ceiling and visibility are reported below

Answer 2

1,000 feet and/or 3 miles.

Question 3

What causes surface winds to flow across the isobars at an angle rather than parallel to the isobars?

Answer 3

Surface friction.

Question 4

Which force, in the Northern Hemisphere, acts at a right angle to the wind and deflects it to the right until parallel to the isobars?

Answer 4

Coriolis.

Question 5

You are on the DME arc at 5,000 feet AGL, and winds are from the southwest at 25 knots. Winds at the surface are from the south at 10 knots. What causes the difference in wind speed and direction at the surface?

Answer 5

The friction between the wind and the surface.

Question 6

What relationship exists between the winds at 2,000 feet above the surface and the surface winds?

Answer 6

The winds at 2,000 feet tend to parallel the isobars while the surface winds cross the isobars at an angle toward lower pressure and are weaker.

Question 7

Winds at 2,000 feet compared to winds at the surface are

Answer 7

higher and go at right angles to the isobars as compared to the winds at the surface due to friction.

Question 8

Surface friction in mountainous areas will cause wind speed to

Answer 8

decrease.

Question 9

The wind is from 230* at 30 knots at 2,000 feet AGL. The surface wind is from 170* at 10 knots. What is the reason for the difference in wind direction and speed?

Answer 9

The earth’s surface causes the wind to turn in a different direction and surface friction slows it down.