Chapter 10 Flashcards
Why are specific humidity and mixing ratio more commonly used in representing atmospheric moisture than
absolute humidity? What is the only way to change the specific humidity or mixing ratio of an air parcel?
Absolute humidity - mass of water vapour / volume of air
Specific humidity - mass of water vapour / total mass of air
Mixed ratio - mass of water vapour / mass of air
Absolute Humidity is less used as it fluctuates easily when the volume or air changes. Specific Humidity and Mixing Ratio are more commonly used because they remain more constant when the volume of air changes. The only way to change is to add or remove water vapour to the parcel of air.
What does the relative humidity represent?
Relative Humidity is the ratio of the amount of water vapour in the air to the maximum amount of water vapour required for saturation at that particular temperature.
When the relative humidity is given, why is it also important to know the air temperature?
It is because an increase in air temperature will result in a decrease in relative humidity vice versa.
Explain two ways the relative humidity may be changed
Change in air temperature or change in water vapour pressure
What is the dew-point temperature?
Dew-point temperature is the temperature to which air would have to be cooled for saturation to occur.
How is the difference between dew point and air temperature related to the relative humidity?
The difference indicates the level of relative humidity. If dew point and air temperature are close, the relative humidity will be higher. If dew point and air temperature are further apart, the relative humidity will be lower.
Why is cold polar air described as “dry” when the relative humidity of that air is very high?
It is considered dry because of the lack of water vapour caused by lower temperature. The relative humidity is close to 100% as dew point and air temperature are very close together.
How can a region have a high specific humidity and a low relative humidity? Give an example.
Desert air dew point and temperature are far apart indicating that the relative humidity is rather low. Since, desert air has a high dew point there will be more water vapour molecules in the air. More water vapour molecules indicates that an higher absolute, specific and mixing ratio humidity.
How much water are annually evaporated into the atmosphere?
1.5 Billion Gallons of water vapour
How much would the earth be covered if the water vapour in the atmosphere condense and fall as rain?
2.5CM (1 Inch)
