the tendency of air to ascend or descend vertically
warming or cooling rates for ascending or descending air masses.
Air cools at different lapse rates
(3) Environmental Lapse Rate Dry Adiabatic Rate (DAR) Moist Adiabatic Rate (MAR)
Environmental Lapse Rate
the actual lapse rate at a particular place and time - can vary by several degrees per thousand meters
Environmental Lapse Rate differs depending on what environmental factors?
(3) - location - season - atmospheric pollution
Dry Adiabatic Lapse Rate (DALR)
the rate at which dry air (RH <100%) cools by expansion as it ascends/warms by compression as it descends - 10 C° per 1000 m
Moist Adiabatic Lapse Rate (MALR)
the rate at which moist (saturated, RH=100%) air cools as it ascends/warms by compression as it descends - 6 C° per 1000 m
Lifting Condensation Level
the altitude at which the dew point temperature, saturation, and active condensation occurs
Clouds are fundamental indictors of ____
overall conditions including: - stability - moisture content - weather
how do clouds form?
Clouds form as air becomes saturated with water
A cloud is an aggregation of tiny moisture droplets and ice crystals that are suspended in air and are great enough in volume and concentration to be visible
Three states of water
Liquid, Solid (ICE), Vapour
When does saturation occur?
- decrease in Air temp - addition of water vapour
Dew Point Temperature
Temperature at which net condensation occurs
Properties of Water
- Polar - Universal Solvent - Surface Tension that occurs due to hydrogen bonding - Capillarity (hydrogen molecules pulling on each other_
Phase change involves the absorption or release of what kind of heat?
absorption or release of latent heat
A process in which ice evaporates directly to water vapour or water vapour freezes to ice
Energy required for a change of state.
mass of water vapour per mass of air at any specific temperature.
Ratio of amount of water vapour actually in air to maximum amount possible at a given temperature.
Portion of total air pressure that results from water vapour molecules (mb).
Two things necessary for raindrop/snow formation (condensation processes)
1. Collision - Coalescence process 2. Bergeron ice-crystal process
Is a (generally stratiform) cloud that occurs at ground level
Maximum Specific Humidity
the maximum mass of water a mass of air can hold at a specific temperature
cloud condensation nuclei, microscopic particles (dust, soot, ash, particles from burned fuel, sea salts)
- Stratus - Cumulus - Nimbostratus - Stratocumulus - Altocumulus - Cirrus - Cumulonimbus -
Stratiform (flat) cloud generally below 2000m
Bright and puffy cumuliform cloud up to 2000m in altitude
Rain-producing stratus clouds (gentle dizzle)
Lumpy, grayish, lowlevel cloud (patchy) near end of the day