Lecture 8 (Humidity, Condensation, and Clouds) Flashcards
The average American family uses more than how many gallons of water per day at home?
300 gallons
What percentage of earths surface is covered in water?
70%
Why is the specific heat capacity of water important?
It stabilizes our temperature
Solid
Molecules move very slowly and are close together
Liquid
Molecules move faster and are more spread apart
Gas
Molecules move very fast and are very spread apart
Evaporation
Changing from liquid(slowly moving) into vapor (fast moving)
Condensation
Changing from vapor (fast moving) into liquid (slow moving)
We will fill a cup with some room temperature water and let it sit on a table for a day or two. What will happen to the water?
The water in the cup would slowly evaporate away
Why is the condensation rate so slow from the cup question?
Because the rate of condensation depends on how much water vapors is in the air.
If we heat up the water, what will happen to the evaporation, condensation, and water vapor content is in the air?
The rate of evaporation increases with increasing temperature. This requires higher and higher rates of condensation to balance the rate of evaporation. Higher and higher rates of condensation means increasing the amount of water vapor in the air
Indices of water vapor content
- water vapor mass
- vapor pressure
-relative humidity
-dew point temperature
Water vapor mass
- absolute humidity
- specific humidity
- mixing ratio
Absolute humidity
Mass of water vapor / volume of air
Specific humidity
Mass of the water vapor / mass of air (including water vapor)
Mixing ratio
Mass of the water vapor / mass of air without water vapor
Saturation vapor pressure
Describe how much water vapor is necessary to make the air saturated at any given temperature
The saturation vapor pressure of water increases with?
Temperature (warmer air can hold more water vapor)
The relative humidity (RH)
(Actual vapor pressure / saturation vapor pressure) * 100
Dew point temperature description
Is the temperature to which air would have to be cooled for saturation to occur
The higher the dew point
The more water vapor in the air
Relative humidity description
Is the ratio of the amount of water vapor actually in the air to the maximum amount of water vapor required for saturation at that particular temperature and pressure
Specific humidity description
The ratio of mass water vapor in a given air parcel to the total mass of air in the parcel
Mixing ratio description
The ratio of mass of water vapor in a given air parcel to the total mass of dry air in the parcel
Relative humidity description
The ratio of the amount of water vapor in the air compared to the amount of required for saturation
Vapor pressure description
The pressure exerted by water vapor molecules in a given volume of air
How to measure dew point temperature?
- dew point hygrometer
- reflecting a light beam off a chilled mirror
- ASOS (automated surface observing system)
Two categories of indices
1- a measure of moisture content ( absolute humidity, specified humidity, mixing ratio, vapor pressure, dew point temperature)
2- a measure of how near the air is to being saturated (relative humidity)
A common misconception
Air with higher relative humidity must have
A common misconception
Air with higher relative humidity must have a greater water vapor content than air with lower relative humidity.
Forms of condensation
- dew
- frost
- fog
- cloud
3 major types of fog
- radiation fog
- advection fog
-upslope fog
Radiation fog
Fog produced by the earths radiation cooling is called radiation fog or ground fog
Advection fog
Warm moist air that moves above a cold surface may become cooled to its dew point temperature, creating an advection fog.
Upslope fog
Is formed as moist air flows up along an elevated plain, hill, or mountain
Nimbostratus
Is a rain cloud that shows layering
Cumulonimbus
Is a rain cloud having pronounced vertical development
Cloud type classification by both
Elevations and appearance
Four types of cloud appearance
- status: layer or sheet like clouds
- cumulus: heal or puffy cloud
- cirrus: curl of hair or wispy cloud
- nimbus: violent rain or rain clouds
