Let us learn about humidity and two types of humidity.

Humidity

Moisture continuously enters and leaves the atmosphere and accordingly characterizes the air. This moisture in the air is called Humidity. This moisture or water vapor condenses into clouds and falls back on Earth in form of Precipitation.

Two types of Humidity: Absolute and Relative Humidity

Two primary measures of Humidity are widely employed while measuring the weather condition of any area: Absolute and Relative Humidity.

Two types of Humidity: Absolute Humidity

Absolute humidity is defined as the actual amount of moisture present in the atmosphere at a certain temperature and volume and differs from place to place and also from time to time in the atmosphere.

Absolute humidity is the mass or weight of vapor per unit of air and is calculated in grams per cubic meter. The amount of absolute humidity decreases from the equator towards the poles. Absolute humidity does not change with the increase or decrease in temperature.

The change in temperature actually changes the capacity of the atmosphere to hold moisture and not the actual amount of moisture. However since air rises upwards, absolute humidity may change. Therefore in weather calculations, absolute humidity is not taken into account.

Two types of Humidity: Relative Humidity

The ratio between the absolute humidity of a given mass of air and the maximum amount of water vapor that it can hold at the same temperature is called relative humidity.

Relative humidity = (Actual amount of water vapor present in the air/ The maximum amount of vapor the air can hold at that temperature) * 100.

The relative humidity is generally expressed in percentage. For example: suppose the air can hold a maximum of 50 grams of water vapor at a given temperature and only 25 grams of water vapor is actually present in it, so the relative humidity will be 50 %.

When the capacity of air to hold moisture and the absolute humidity of air is the same, the air is said to be saturated. The relative humidity of saturated air is 100% and that of dry air is 0%. The relative humidity of air decreases with an increase in temperature and vice versa.

The relative humidity is directly related to human health. That is why the equatorial region with high temperatures and high relative humidity and the tropical deserts with very low relative humidity are unfavorable for human health. The absolute humidity determines the amount of precipitation while the relative humidity tells us about the possibility of precipitation.

Two types of Humidity: Questions

1. The relative humidity that can hold 100 gm of water vapor but is holding 45 grams of water vapor is
(i) 45 grams
(ii) 25%
(iii) 25 grams
(iv) 45%

2. The relative humidity of air decreases with
(i) Increase in pressure
(ii) Increase in volume
(iii) Decrease in temperature
(iv) Increase in temperature

3. Absolute humidity is calculated in
(i) Percentage
(ii) Grams per square meter
(iii) Kilograms per cubic meter
(iv) Grams per cubic meter

4. What is the air called, if the capacity of air to hold moisture and absolute humidity of air is the same?
(i) Dry
(ii) Humid
(iii) Heavy
(iv) Saturated

5. The relative humidity tells us about _____.
(i) Amount of precipitation
(ii) Amount of fog
(iii) Possibility of mist
(iv) Possibility of rainfall

Read More: What is Precipitation: Process, Condition Necessary, and Distribution - Class 9