What sequence of clouds is typically observed during the passage of a warm front?
-
A
In coastal areas during daytime wind from the coast and forming of cumulus clouds, dissipation of clouds during evening and night.
-
B
Squall line with showers of rain and thunderstorms (Cb), gusting wind followed by cumulus clouds with isolated showers of rain.
-
C
Wind becoming calm, dissipation of clouds and warming during summer; formation of extended high fog layers during winter.
-
D
Cirrus, thickening altostratus and altocumulus clouds, lowering cloud base with rain, nimbostratus.
Refer to figure.
A warm front can be defined as warm air replacing cold air. As the warm, less dense air overtakes and displaces the cold air, it rides up and over the denser cold air while advancing. The air behind the warm front is warmer and moister than the air ahead of it, resulting in warmer and more humid conditions once the front passes.
All the warm front weather occurs at and ahead of the front's surface position, extending forward for 600 to 700 NM.
The first indication of the approaching warm front is the arrival of high cirrus clouds. As the front draws nearer, the cloud base gradually lowers, and the clouds thicken into altostratus and altocumulus. Approximately 200 NM from the surface position of the front, the altostratus becomes thick enough to produce rain. Closer to the front, nimbostratus clouds predominate, with layers of altostratus above them extending several thousand feet above the surface. Rain falling from the altostratus can evaporate, saturating the air just ahead of the front, sometimes creating additional very low clouds such as stratus and fractostratus ahead of the frontal surface.
Your Notes (not visible to others)
This question has appeared on the real examination, you can find the related countries below.
-
Austro Control
Use Keyboard Shortcuts
