,ODULE 3 Flashcards
is the general term for all forms of moisture emanating from the clouds and falling to the ground.
PRECIPITATION
TYPES OF PRECIPITATION
CONVECTIONAL PRECIPITATION
FRONTAL PRECIPITATION
OROGRAPHIC PRECIPITATION
CYCLONIC PRECIPITATION
This type of precipitation is in the form of local whirling thunderstorms and is typical of the tropics.
The air close to the warm earth gets heated and rises due to its low density, cools adiabatically to form a cauliflower shaped cloud, which finally bursts into a thunderstorm.
When accompanied by destructive winds, they are called ‘tornados’.
CONVECTIONAL PRECIPITATION
When two air masses due to contrasting temperatures and densities clash with each other, condensation and precipitation occur at the surface of contact.
This surface of contact is called a ‘front’ or ‘frontal surface’.
FRONTAL PRECIPITATION
If a cold air mass drives out a warm air mass, it is called a ‘cold front’.
COLD FRONT
If a warm air mass replaces the retreating cold air mass, it is called a ‘warm front’.
WARM FRONT
If two air masses are drawn simultaneously towards a low- pressure area, the front developed
is stationary and is called a
‘stationary front’.
STATIONARY FRONT
Cold fronts move faster than warm fronts and usually overtake them, the frontal surfaces of cold and warm air sliding against each other. This phenomenon is called occlusion, and the resulting frontal surface is called an ‘occluded front.
OCCLUDED FRONT
This type of precipitation is caused by the uplift of moist air as it flows over a mountain or other elevated terrain.
As the air rises, it cool and condenses, forming clouds
and precipitation.
OROGRAPHIC PRECIPITATION
This type of precipitation is due to lifting of moist air converging into a low-pressure belt, due to pressure differences created by the unequal heating of the earth’s surface.
Here the winds blow spirally inward counterclockwise in the northern hemisphere and clockwise in the southern hemisphere.
CYCLONIC PRECIPITATION
(also called hurricane or typhoon) of comparatively small diameter of 300-1500 km causing high wind velocity and heavy precipitation,
tropical cyclone
large diameter up to 3000 km causing widespread frontal type precipitation.
extra tropical cyclone
a light steady rain in fine drops (0.5 mm) and intensity less than 1 mm/h.
Drizzle:
the condensed water vapor of the atmosphere falling in drops from the clouds of sizes larger than 0.5 mm. The maximum size is about 6 mm.
Rain
freezing of drizzle or rain when they come in contact with cold objects.
Glaze
frozen rain drops while falling through air at subfreezing temperature.
Sleet