Our earth is surrounded by a huge blanket of air called atmosphere.
Nitrogen (78%) and oxygen (21%) are two gases which make up the bulk of the atmosphere.
Carbon dioxide, helium, ozone, argon and hydrogen are found in lesser quantities.
Carbon dioxide released in the atmosphere creates a green house effect by trapping the heat radiated from the earth. It is therefore called a greenhouse gas
Atmosphere has 5 layers. They are:
Troposphere
Most important layer
Average height is 13 km
Weather phenomena occurs here
Stratosphere
Extends up to 50 km
Ideal for flying aeroplanes
Contains ozone layer
Mesosphere
Extends up to 80 km
Meteorites burn in this layer
Thermosphere
Extends between 80-400 km
Temperature increases with height
Helps in radio transmission
Exosphere
Light gases like helium and hydrogen float here
Weather is this hour-to-hour, day to day condition of the atmosphere.
The average weather condition of a place for a longer period of time represents the climate of a place.
The degree of hotness and coldness of the air is known as temperature.
Insolation is the incoming solar energy intercepted by the earth.
Air pressure is defined as the pressure exerted by the weight of air on the earth’s surface.
The air always moves from high pressure areas to low pressure areas.
The movement of air from high pressure area to low pressure areas is called wind.
Winds are of three types:
Permanent Winds
Blow throughout the year
Blow in a particular direction
Trade winds, westerlies and easterlies are permanent winds
Seasonal winds
Change direction in different seasons
Local winds
Blow only during a particular period
Eg: loo
Moisture in the air at any time, is known as humidity.
Precipitation that comes down to the earth in liquid form is called rain.
On the basis of mechanism, there are three types of rainfall: the convectional rainfall, the orographic rainfall and the cyclonic rainfall.
Other forms of precipitation are snow, sleet, and hail.
