These Water in the Atmosphere Class 11 Geography Notes explain atmospheric moisture, humidity, evaporation, condensation, cloud formation and precipitation. The chapter discusses relative humidity, dew point, forms of condensation, cloud types, rainfall types and world distribution of precipitation.
These NCERT notes are useful for UPSC, SSC, Railways, State PSC, CUET and CBSE Board Exams. The chapter is important for understanding weather phenomena, atmospheric moisture processes and global rainfall patterns.
This chapter explains atmospheric moisture, humidity, evaporation, condensation, cloud formation and precipitation. It highlights how water circulates through the atmosphere and influences weather and climate across the world.
Humidity is the amount of water vapour present in air.
Relative humidity is the percentage of moisture present in atmosphere compared to its full capacity at a given temperature.
Air holding moisture to full capacity is called saturated air.
Dew point is the temperature at which saturation occurs.
Evaporation is the transformation of water from liquid to gaseous state mainly due to heat.
Heat required to convert liquid into vapour without temperature change.
Condensation is the transformation of water vapour into water caused by loss of heat.
Fog mixed with smoke is called smog.
Clouds are masses of minute water droplets or ice crystals formed by condensation in free air.
| Cloud Type | Category |
|---|---|
| Cirrostratus | High cloud |
| Cirrocumulus | High cloud |
| Altostratus | Middle cloud |
| Altocumulus | Middle cloud |
| Stratocumulus | Low cloud |
| Nimbostratus | Low cloud |
| Cumulonimbus | Vertical cloud |
Precipitation is the release of moisture after condensation in liquid or solid form.
Caused by cyclones and fronts.
| Region | Rainfall |
|---|---|
| Equatorial belt | Over 200 cm |
| Interior continental areas | 100–200 cm |
| Tropical interiors | 50–100 cm |
| Rain shadow areas | Less than 50 cm |
Relative humidity is the percentage of moisture present in air compared to its maximum capacity.
It is the temperature at which air becomes saturated.
Smog is fog mixed with smoke.
Dry area on the leeward side of mountains.
Cirrus clouds are found at highest altitude.