occurs over a shorter time period.

affects a larger area.

is free of rain.

has an updraft

2,3 and 1

5,6 and 2,3

2,3 and 5,6

4 and 5,6

On the Eastern side of the ridge, at the same height as the ridge.

On the Western side of the ridge, halfway up its slope.

On the Eastern side of the ridge, halfway up its slope.

On the Western side of the ridge, at the same height as the ridge.

Warm moist air arrives under an unstable thermal stratification on the windward side. Lee waves develop in the unstable stratification on the leeward side.

A strong heating of the air on the windward side, contrasting with strong cooling on the leeward side of the mountain range.

A strong large-scale wind increase up to high levels and blowing approximately perpendicular towards the mountain range under a stable thermal stratification.

Lee waves form when strong winds blow parallel to the mountain range and split up into two branches. The wind shear across the crest causes lee waves.

the Earth's surface and nocilucent clouds in the mesosphere.

two thunderstorms, of which one is developing and the other dissipating.

the top of the thunderstorm and the surrounding air at the same altitude.

the Earth's surface and the cloud or between different parts of the cloud.

An extremely low relative humidity

A strong temperature inversion

Contamination such as sand and dust reducing engine performance

A severe downdraft

a change of vertical wind speed with horizontal distance.

a change of horizontal wind direction and / or speed with height.

a change of horizontal wind direction and / or speed with horizontal distance.

a horizontal shear of vertical wind.

Satellite broadcast

Special AIREP

Company message via ACARS.

On a VOR frequency

-45°C and -60°C

 -15°C and -40°C.

0°C and -15°C.

-30°C and -55°C

In the METAR, the surface wind is the average of the last 10 minutes. In the ATIS, it is the average of the last 5min.

In the METAR, the surface wind is the average of the last 10 minutes. In the ATIS, it is the average of the last 2min.

Because the surface wind is measured at different locations and heights.

In the METAR, the surface wind is the average of the last 2 minutes. In the ATIS, it is the average of the last 10min.