1. Day 9 - Humidity
Science 10 Weather

2. Humidity The amount of water vapour in the air
Humidity The amount of water vapour in the air **warm air can hold more water vapour than cold air

3. Water in the Air
Air is saturated when it contains the maximum amount of water vapour possible at that temperature.
Water will continue to evaporate until the air is saturated.
When air cools, the water vapour it contains condenses into liquid water (clouds, fog, rain)

4. Relative Humidity The amount of water vapour in the air (as a percentage of the amount of vapour that the air would have if saturated)

5. Absolute Humidity The actual quantity of water vapour in the air (in grams of water vapour per kilogram of air)

6. Absolute Humidity

7. Saturated Air When there is as much water vapour in the air as the air can hold

8. Saturated Air
A : Condensation
B : Evaporation
C : Saturated Air

9. Dew Point
The temperature at which the air is saturated with water vapour so that it condenses into liquid.

10. Humidity and the Humidex Scale
The Humidex scale was created by Environment Canada.
This scale takes into account both the temperature and the relative humidity of the air.
The Humidex value indicates how warm a given temperature will feel to the average person when relative humidity is taken into account.

11. Humidity and the Humidex Scale
On a summer day when the relative humidity is high, you feel much hotter than when the temperature is the same but it is less humid.
A weather forecast may indicate that the temperature is 35 degrees Celsius, but that it feels like 40 degrees Celsius on the Humidex Scale.
Why do you experience the air around you as warmer?
An increase in relative humidity reduces the capacity of perspiration (sweat) from evaporating and in return cooling your body, causing you to feel hotter!

12. Humidex from Temperature and Relative Humidity Readings