Term
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Definition
| refers to the tendency of an air parcel with its water vapor either to remain in place or to change vertical position by rising or falling |
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Term
| Environmental Relapse Rate |
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Definition
| the temperature profile of the atmosphere; determines air stability |
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Term
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Definition
| the condition of the air when the ELR is less than the DAR; usually results in no uplift of air but subsidence or sinking air; often associated with high pressure cells; clear skies, maybe few stratus clouds |
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Term
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Definition
| the condition of the air when ELR is greater than the DAR; often occurs during the warmest months and on clear days; often leads to cloud formation, cumulus clouds and precipitation; low pressure cells; results in uplift of the air parcel |
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Term
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Definition
| the condition of the air when the ELR is between the DAR and the SAR, SAR is less than ELR which is less than the DAR; air can vary between stable and unstable; usually if air is saturated, upper portion is unstable; if air is unsaturated, then lower portion is stable |
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Term
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Definition
| the process of warming a parcel of air at the surface by conduction, then the whole parcel rising into the atmosphere since it's warmer than surrounding air |
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Term
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Definition
| the process by which air is forced to rise over a mountain range or other elevated land barrier and thus cool adiabatically; precipitation occurs on the windward side of the mountain; little or no precipitation occurs on the leeward side; may create Rain Shadow Desert |
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Term
| Frontal Wedging (Lifting) |
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Definition
| the process by which cold, dense air acts similarly to a mountain barrier forcing warmer, less dense air to rise over it; leading mass of cold air is called cold front and leading mass of warm air is called warm front; this mechanism is known as a Mid Latitude Wave Cyclone (frontal system) |
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Term
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Definition
| the process by which winds come together from opposite directions and are forced to rise due to compression or squeezing |
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Term
| Bergeron Process (Ice-Crystal Process) |
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Definition
| water less than 0 degrees Celsius is called supercooled; difference in vapor pressure allows supersaturation to exist; RH > 100%; ice crystals collect more water vapor than they lose thus growing to make snow crystals and then snowflakes |
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Term
| Collision-Coalescence Process |
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Definition
| primary process in tropics for raindrop formation; max size of raindrop = 5 mm (any bigger is pulled apart by friction); this is the idea behind cloud seeding |
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Term
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Definition
| at least 0.5 mm to 5 mm in size; from nimbostratus and cumulonimbus clouds; frozen --> liquid (before it hits the ground) & liquid --> liquid (as it hits) |
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Term
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Definition
| 1-2 mm in size; water vapor deposited as ice crystals |
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Term
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Definition
| .5 - 5 mm in size; freezes as it falls and is a frozen raindrop before it hits the ground; frozen --> liquid --> frozen |
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Term
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Definition
| .5 - 5 mm in size; supercooled raindrops which freeze on contact with solid objects or surfaces |
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Term
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Definition
| 5 - 10 mm in size; hard, round pellets or lumps of ice; only produced in large cumulonimbus clouds/thunderstorms |
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Term
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Definition
don't have the same characteristics on both the east and west side; eastside- subsidence, temperature inversion, and upwelling of cold ocean currents leads to greater instability and wet conditions
westside- little subsidence, more uplifting, convergence, and warms ocean currents leads to greater instability and wet conditions |
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Term
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Definition
| due to mountain barriers and orographic effects; leeward side often are much drier than windward side |
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Term
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Definition
| an annual cycle of dryness and wetness with seasonally shifting winds produced by changing atmospheric pressure systems |
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Term
| What do clouds, fog and dew have in common? |
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Definition
| must form from saturated air; must have a surface on which water vapor can condense |
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Term
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Definition
| water that has condensed into an object near the ground when their temperature has fallen below the dew point temp of the surface air; forms on ground, vegetation, a car, or similar surface |
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Term
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Definition
| dew which has formed (liquid) then frozen (solid) condensation, then freezing (water vapor to liquid to solid) |
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Term
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Definition
| covering of ice produced by deposition when the dew point temp is below freezing |
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Term
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Definition
| a form of condensation best described as a dense, visible aggregation of minute droplets of water or tiny ice crystals; need condensation nuclei; formed either by cooling the air temp to the dew point temp or by adding more water vapor |
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Term
| Two criteria for classifying clouds |
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Definition
1) height of cloud base above the surface
2) degree of vertical development |
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Term
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Definition
| "layer" horizontal development |
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Term
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Definition
| "heap" or "cotton balls," vertical development |
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Term
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Definition
| "curl of hair" clouds found in the highest up atmosphere, composed of ice crystals |
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Term
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Definition
| "violent rain," cumulonimbus and nimbostratus |
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Term
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Definition
| four main categories of this; condensation can occur in some instances where the RH is as low as 75% - 80% |
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Term
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Definition
| produced over land when radiational cooling down the air temp to dew point temp; also known as ground fog; valley fog is of this type, it forms in low lying areas from cold, heavy air draining downhill (known as cold air drainage) |
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Term
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Definition
| occurs when warm, moist air moves over a cold surface and air cools to below its' dew point temp |
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Term
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Definition
| created when warm, moist air flows up along an elevated plain, hill, or mountain |
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Term
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Definition
when the air reaches saturation by adding water vapor and not decreasing the air temp; two main types: steam fog- forms when cold air moves over warm water; the warmer water evaporates into the saturated cold air causing condensation and fog formation
frontal fog- forms as warm raindrops evaporate in a cool air mass as they fall |
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Term
| Adiabatic Temperature Change |
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Definition
| changing the temp of the air without adding or subtracting heat (simply the result of compressing the air or allowing it to expand); temp changes without heat being subtracted or added; results are that rising air expands and cools or sinking air is compressed and warms |
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Term
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Definition
| the rate at which the air temp changes as it rises or falls through the atmosphere |
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Term
| Dry Adiabatic Rate (Dry Adiabatic Lapse Rate) (DAR or DALR) |
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Definition
| when the air is unsaturated; it is a constant rate of 1 degree C/100m or 10 degrees C/1000m; thus rising air cools/sinking air warms at 1 degree per 100m |
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Term
| Saturated Adiabatic Rate (Saturated Adiabatic Lapse Rate) (SALR or SAR) |
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Definition
| when the air is saturated; it is not a constant rate, but a variable rate: 5-9 degrees C/1000m; this is because condensation releases latent heat, thus slowing the rate of cooling (or warming) |
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Term
| Stable Atmospheric Conditions |
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Definition
| occurs when the air inside the parcel is cooler than the surrounding air (saturated conditions) |
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Term
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Definition
| height at which condensation occurs; where cloud formation begins (usually seen as the bottom of a cloud mass); RH 100%; air temp = dew point temp |
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