Moisture Flashcards
(21 cards)
What is the process of cloud formation?
Cloud is formed when condensation occurs, when water vapour becomes visible.
What conditions are necessary for cloud formation?
Sufficient relative humidity and solid particles such as soil, dust, smoke, or salt.
What happens to the air temperature for cloud to form?
The air temperature must be cooled to the dewpoint temperature.
How can cloud formation occur through precipitation?
Cloud can also be formed by the evaporation of precipitation.
What is relative humidity?
The percentage of saturation of air for a given temperature.
What is dewpoint?
The temperature to which air must be cooled to reach 100% saturation.
What is the dry adiabatic lapse rate (DALR)?
3° C per 1,000 ft.
What is the saturated adiabatic lapse rate (SALR)?
1.5° C per 1,000 ft.
What occurs when the dewpoint temperature equals the ambient temperature?
Cloud forms.
What is latent heat release?
Heat released during the change of state from gas to liquid at the dewpoint.
What is the process of condensation?
The change of state from water vapour (gas) to liquid water droplets as a result of cooling.
What is sublimation?
The process where water vapour freezes directly into solid without becoming liquid first.
What is evaporation?
The change of state from visible water vapour to invisible water in its gas form.
What is virga?
Streamers of precipitation that evaporate before reaching the surface.
What is the adiabatic lapse rate for unsaturated air?
DALR of 3.0° C per 1,000 ft.
What is the adiabatic lapse rate for saturated air?
SALR of 1.5° C per 1,000 ft.
How do you calculate cloud base using surface temperature and dewpoint?
Cloud base = (Surface temperature - Dewpoint) / DALR * 1,000 ft.
Fill in the blank: The freezing level is at _______.
[0° C]
True or False: Saturation can occur when moisture is added by the evaporation of raindrops.
True
How do you determine the freezing level above the cloud base?
Use SALR to calculate from the cloud base to the freezing level.
What is the significance of latent heat in cloud formation?
It causes differing lapse rates associated with cloud formation.
