Temperature-Moisture Relationships Flashcards
relative humidity _____ as temperature increases
decreases
For qualifying the amount of moisture in the atmosphere, the two most common reference points are the ___ ___ and the ___ _____.
dew point
relative humidity
rule of thumb for relative humidity with temperature
relative humidity doubles with each 20 degF (11 degC) decrease, or halves with each 20 degF (11 degC) increase in temperature
Water vapor capacity increases as _____ _____.
temperature increases
At very high altitudes where air is very cold, clouds consist of ____ ____ _____.
tiny ice crystals
Example: Low temperature air can hold 2 parts water vapor, warmer air 6 parts water vapor, and hotter air 12 parts water vapor. When the hotter air is cooled, it must lose some of its water vapor through _______.
condensation
relative humidity (definition)
the ratio of the actual amount of water vapor in a given volume of air to the amount which would be present if the air were saturated at the same temperature
Energy per pound required to change water from liquid state to vapour state
972 Btu/lbm
(2261 kJ/kg)
Water heat of fusion in BTUs
144 Btu/lbm (335 kJ/kg)
(melting ice)
dew point
the temperature to which a parcel of air must be cooled to reach its saturation point
Water energy required to go from 32 F to 212 F, per lbm
182 Btu
(192 kJ)
When air is cooled to its saturation point, _____ occurs in the form of clouds and perhaps precipitation.
condensation
The ____ of air influences the amount of water vapor that can be bound to the molecules of air.
temperature
Approximately ______ of heat energy per pound of water has been stored in moisture bound to the air. This amount of energy is released into the air when the moisture condenses and freezes.
1,300 Btu
(1,372 kJ)
Given a parcel of air, the dew point of that air will remain the same as will the amount of moisture in the parcel, regardless of ______.
temperature
