(1) The ratio of the water vapour content of the mixture to the total air content on a mass basis.
(2) It is expressed in grams of vapour per kilograms of air.

Torrid Zone
Temperate Zone
Frigid Zone

Temperature decreases with increasing height is known as Lapse rate, which is 6.5 degree celsius per 1000 meters in troposphere.

Planetary Winds are the winds which blow almost in the same direction throughout the year.
So, they are called as Permanent or planetary winds.
E.g: Trade winds, westerlies and Polar easterlies.

(i) Insolation is the solar radiation that reaches the earth's surface.
(ii) It is measured by the amount of solar energy received per square centimetre per minute.
(iii) Insolation affects temperature.
(iv) The more the insolation the higher the temperature.

Low humidity:
(1) Eyes become dry and irritated, skin gets Haky and itchy and the low humidity inflames and dries out the mucous membrane lening the respiratory tract.
(2) As a result, the risk of cold, flu, and other infections is substantially increases.
High humidity:
If you have a chronic lung condtions such as asthma, you may struggle even more with changing weather condtion.

The horizontal movement of air is called wind.
The winds move from high pressure to low pressure.
Winds get their name from the direction from which they blow i.e, wind blows from south west is called southwest monsoon.
The wind systems are broadly categorized into three as follows.
i) Planetary winds
ii) Seasonal winds
iii) Local winds
Planetary winds:
These Winds are the ones which blow almost in the same direction throughout the year. So, they are called as Permanent or planetary winds.
Eg: Trade winds, Westerlies and polar easterlies.
Seasonal winds:
Seasonal winds are those which change their direction according to season in a year.
They are called as monsoon winds.
These winds blow from sea to land during summer and land to sea during winter.
Local winds:
These winds are the winds blow over a small area only during a particular time of a day or a short period of a year.
Eg: Land breeze and sea breeze.

1. The temperature of a unit volume of air at a given time is measured in scales like Celsius, Fahrenheit,
2. Meteorologist measures the temperature by the Thermometer, Stevenson screen and minimum and maximum Thermometer.
3. Atmosphere is mainly heated by outgoing radiation from 2 to 4 pm.
4. So the maximum temperature is recorded between 2 and 4 pm regularly and minimum temperature is recorded around 4 am before sunrise.