A parcel of air with a temperature of 70° F and a dew point temperature of 48°F.
ID: 105325 • Letter: A
Question
A parcel of air with a temperature of 70° F and a dew point temperature of 48°F.
(1) Is the relative humidity of the parcel 100%? Why?
(2) Assume the air is forced upward by a mountain range, will it cool at the dry or moist adiabatic rate until it reaches the condensation level? Why?
(3) What is the condensation level or altitude (in ft) of this air parcel?
(4) Above this level, will the rising air begin cooling at the dry or moist adiabatic rate? Do you think the formation of clouds is possible?
Explanation / Answer
1. Relative humidity of 100% means the dew point is the same as the current temperature.
Relative Humidity= 100% indicates the dew point is equal to the current temperature .
Relative humidity gives the ratio of how much moisture the air is holding to how much moisture it could hold at a given temperature. When the moisture content remains constant and temperature increases, relative humidity decreases. so it will be 45%
2. As given in question that dew point is less than the temperature, and air parcel is not saturated. so water vapor will not condense so there will be no fog and no dew.
3. If there is a cloud in the parcel it will evaporate, water will evaporate to keep the relative humidity at 100% and the dew point temperature equals the air temperature. Parcels which contain an evaporating cloud warm at a rate of 6°C for every 1000 meters the parcel is lowered until the entire cloud has evaporated.
4.
Temperature of the atmosphere decreases as we go up. The atmosphere is conditionally unstable much of the time. It c depends on how the temperature of the atmosphere changes at different levels.
Cold air lying over warm air is unstable, since the warm buoyant air below will want to rise, while the cold, heavy air above will want to sink. Changes in the atmosphere which reinforce "cold over warm" will decrease the stability of the atmosphere or unstabilize the atmosphere.
Air Temperature= 70° F Dew Point Temperature= 48° FRelative Humidity= 100% indicates the dew point is equal to the current temperature .
Relative humidity gives the ratio of how much moisture the air is holding to how much moisture it could hold at a given temperature. When the moisture content remains constant and temperature increases, relative humidity decreases. so it will be 45%
2. As given in question that dew point is less than the temperature, and air parcel is not saturated. so water vapor will not condense so there will be no fog and no dew.
3. If there is a cloud in the parcel it will evaporate, water will evaporate to keep the relative humidity at 100% and the dew point temperature equals the air temperature. Parcels which contain an evaporating cloud warm at a rate of 6°C for every 1000 meters the parcel is lowered until the entire cloud has evaporated.
4.
Temperature of the atmosphere decreases as we go up. The atmosphere is conditionally unstable much of the time. It c depends on how the temperature of the atmosphere changes at different levels.
Cold air lying over warm air is unstable, since the warm buoyant air below will want to rise, while the cold, heavy air above will want to sink. Changes in the atmosphere which reinforce "cold over warm" will decrease the stability of the atmosphere or unstabilize the atmosphere.
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