About 70 percent of the earth is water; most of it is in its liquid form in the ocean.
In atmosphere, exists in all three states in the atmosphere, liquid, gas, and solid.
Evaporation-liquid to gas, can happen any time you have an input of energy, the
more evaporation the more gas molecules you will get.
Condensation- return of some of gas molecules, coming out of the air and
condensing into liquid form
The balance between evaporation and condensation is called saturation, when
there is the same amount of both. Usually a relative percentage
If you have a saturated atmosphere and you add more water through evaporation,
then you have to have some type of cloud or condensation to balance it out
How do we know if the air is saturated? How close to saturation?
Dew Point Temperature- The hypothetical temperature of the air at which you
would get saturation---the closer the temperature is to the dew point temperature the more
moisture there is in the air.
The higher the dew point temperature is the more moisture.
The temperature in the air is always equal to or greater than the dew point
Vapor pressure-pressure exerted by water molecules. The warmer the air is the
more evaporation and as a result the vapor pressure would be higher. (Exponential
“Warm air holds more water” better way to say this warm air promotes
Saturation Vapor Pressure- the maximum possible water vapor in an
atmosphere. Higher in warm air mass than it is cold air mass
Humidity- amount of moisture in the air
Absolute humidity-specific density of water vapor, mass of water divided
by volume of room
Specific humidity- the mass of water vapor divided by the mass of all the
air molecules, theoretical concept, but can be calculated, useful for comparing humidity
at different locations
Relative humidity- amount of water vapor divided by the maximum
possible water vapor, based on temperature, as temperature goes up, the relative humidity
goes down. Warmest time of day typically has the lowest relative humidity, the coldest
time of day has the highest relative humidity. If the relative humidity equals 100 percent
means there is saturated air, may result in fog, dew, or rain.
-Hair Hygrometer-measures humidity
-Sling psychomotor- two thermometers, one with a cotton cloth wick, wet the wick, sling
around, water starts to evaporate, the temperature starts to drop, compare the temperature
Why do we care about saturation?
Saturated-active condensation, which forms clouds (high or low)
How does air become saturated?
1- Add more water vapor and keep temperature constant