KERALA PSC / PHYSICAL GEOGRAPHY / CLOUDS / NOTES / OBJECTIVE QUESTIONS / STUDY MATERIALS / GENERAL KNOWLEDGE

 

KERALA PSC / PHYSICAL GEOGRAPHY / CLOUDS / NOTES / OBJECTIVE QUESTIONS / STUDY MATERIALS / GENERAL KNOWLEDGE

KERALA PSC / PHYSICAL GEOGRAPHY / CLOUDS / NOTES / OBJECTIVE QUESTIONS / STUDY MATERIALS / GENERAL KNOWLEDGE

·      Clouds are a visible mass of small water drops or ice crystals formed by the condensation of water vapour in the atmosphere, usually at a considerable height above the earth’s surface.

·      Clouds are caused mainly by the adiabatic cooling of air below, its dew point

·      Clouds are grouped into low middle and high clouds according to the altitudes they occur at

·      High clouds include cirrus, cirrocumulus and cirrostratus

Ø Cirrus clouds are high, white & thin. They are composed of ice crystals. They form delicate patches and give a fibrous and feathery appearance

Ø Cirro Cumulous Clouds: These clouds appear as small white flakes or small globular masses usually without shadows. They are usually arranged in groups lines or ripples

Ø Cirro Stratus clouds: as sheets of layer that covers much or all of the sky and giving it a milky appearance

·      Medium clouds include alto cumulus and alto stratus

·      Altocumulus: Globular, bumby-looking clouds which have a flattened base.

Ø Altostratus – grayish, water looking cloud

·      Low clouds include stratocumulus, stratus, nimbostratus, cumulus and cumulo nimbus

·      Strato cumulus – Soft gray cloud, arranged in a regular pattern.

Ø Stratus – low uniform layers of clouds resembling fog

Ø Nimbostratus – Fog like low cloud brings dull weather which is usually accompanied by drizzle

·      Cumulous: These are thick, dense clouds. The upper surface is dome shaped with a cauliflower structure. They have a flat base and of fair weather type.

·      Cumulo Nimbus: Heavy masses of cloud, whose summits rose like mountains or towers. An anvil shaped top is its characteristic. It is accompanied by heavy showers, thunderstorms and sometimes hail.

·      Precipitation is the formation of water particles or ice within the cloud that falls towards the earth’s surface. It occurs when condensation takes place rapidly within the cloud

·      Precipitation in the form of ice-pellets(hail stones) that develops in and fall from cumulo nimbus clouds, either at a cold front or where intense heating of the surface causes rapidly ascending convection currents called Hails.

·      The dew point of the condensing air is below the freezing point, it leads to conversion of water vapour into small crystals of ice and the resulting precipitation in the form of snowfall.

·      Humidity is the degree of water vapour present in the air. For any specified temperature, there is a definite limit to the maximum quantity of moisture that can be held by the air. This limit is known as the saturation point.

·      Humidity can be measured by means of a hygrometer

·      Relative humidity is the ratio between the amount of water vapour actually present in an air mass and the maximum amount that the air mass can hold at that temperature. It is expressed in terms of percentage

·      Vapour Pressure: The amount of pressure exerted by a given column of air differs according to the varying amount of water vapour present in it. That part of barometric pressure due to water vapour alone is known as vapour pressure.

·      Vapour pressure is maximum at the equator (about) 30 mb) and decreases towards the poles (less than 10 mb)

·      Dew is the moisture deposited in the form of water droplets on the earth’s surface or on objects near the earth’s surface

·    Dew point is the temperature at which air is fully saturated and below which condensation normally occurs

·      Condensation is the physical process of transformation from the vapour to liquid state. Condensation occurs when temperature reaches the dew point

·      Frost is a weather condition that occurs when the air temperature is at or below 0ºC. The moisture on the ground surface and objects, freezes to form an icy deposit.

KERALA PSC / PHYSICAL GEOGRAPHY / CLOUDS / NOTES / OBJECTIVE QUESTIONS / STUDY MATERIALS / GENERAL KNOWLEDGE