Atmospheric Humidity Flashcards
What’s the percentage of vapor at the surface?
0-4%
What is Dalton’s law of partial pressure?
the total pressure inside the parcel is equal to the sum of the pressures of the individual gases.
At what time is vapor most prevalent?
vapor is most prevalent during the summer
What is vapor?
the liquid water evaporates into the air more than the vapor that’s condensing
When molecules escaping from liquid balanced by the number returning (condensing) means?
air is saturated
What does the saturation vapor pressure depend on?
only on the temperature
What’s the pattern between the increase of temperature to saturation vapor pressure?
saturation vapor pressure will increase (but the evaporation has to equal the amount being condensed); it takes more water vapor to saturate the air
What is Cloud Condensation Nuclei?
liquid water condensing into cloud droplets
What makes up CCN?
salt, soil particles, ash, dust, pollutants, aerosols, etc.
When does condensation take place?
condensation happens when the air is cooled
What is the relationship between cooling air and saturation vapor pressure (es)?
cooling air lowers the saturation vapor pressure
What is absolute humidity (rho)?
mass of water vapor/volume of air
When does absolute humidity vary?
absolute humidity varies as air volume changes whereas water vapor remains constant
What is specific humidity (q)?
mass of water vapor/mass of air
What is specific humidity conservative for?
pressure (temperature) change
What is the mixing ratio?
mass of water vapor/mass of dry air
What’s the relationship between specific humidity and mixing ratio (air parcel)?
they both remain constant as long as water vapor is not added or removed from the parcel because the total of molecules remain constant as the parcel expands or contracts
What is relative humidity?
the amount of water vapor (e or vapor pressure) /maximum possible amount of water vapor at a given temperature (es or saturation water vapor)
What is RH in close proximity with?
measures proximity to saturation
What is RH not conservative for?
pressure and temperature change
With no change in air temperature, adding water vapor, what is going to happen to relative humidity?
relative humidity is going to increase as the air approaches saturation
No changes in water vapor, an increase in air temperature causes the relative humidity to do what?
lowers the relative humidity; whereas if there’s a decrease in air temperature, relative humidity increases
When is RH at its highest?
when the surface is at its coldest
What is dew point temperature (Td)
temperature below which any further cooling produces condensation
What is the relationship between air temperature and the dew point temperature?
when they both equal one another, RH is 100%
What happens to form the dew point temperature?
Latent heat is released and dew point drops very slowly as vapor is converted to liquid
What is frost point (Tf)?
dew point below freezing (Td<32 degrees F)
When and where is dew point at its highest?
around the Gulf of Mexico, and air is more humid in the summer
What is wet bulb temperature (Tw)?
lowest temperature attained by evaporating water into the air
What happens during the process of wet bulb temperature?
evaporation removes heat from the air and the temperature drops (T minus Tw= wet bulb depression)
What is the dew point depression?
T minus Td
What’s the relationship between wet bulb temperature and dew point temperature?
wet bulb temperature will always be higher than the dew point temperature
What instrument is used to measure water vapor content of the air?
Psychrometer
