Weather Flashcards
What happens to the stability of the air as lapse rate increases?
Stability decrease
Cold front occlusion is…
Cold air replacing warmer air
What visible signs indicate extreme turbulence in thunderstorms?
Cumulonimbus clouds, very frequent lightning and roll clouds
The most destructive winds, heavy hail, and tornadoes are generally associated with
squall lines
Flying over a turbulent mountain range, downdrafts caused by mountain waves will be found
on the crest and downwind side of the mountain range for hundred of miles
Temperature of a rising parcel of air decrease by about…
2.5 C / 1000 ft
Cumuliform Clouds
form in unstable air. The greater the convective lift, the taller the clouds and more severe the turbulence. Can extend 60,000 ft. Associated with lightning, thunderstorms, hail, severe turbulence.
Nimbus Clouds
Any cloud that bring steady precipitation
latin for rain
Cirriform Clouds
Thin, wispy, fibrous filaments. Form at high alt. 20,000 ft or greater
Stratiform Clouds
Sheet-like layers form in stable air
Changes in terrain elevation that force air aloft…
orographic lifting
Unstable air characteristics
-moderate to severe turbulence
-showery precipitation
-Cumulus (vertical) clouds
-good visibility
Stable air characteristics
-little to no turbulence
-contiguous precipitation
-stratiform (layered ) clouds
-poor visibility
The US high-level significant weather prog. chart forecasts weather for what altitudes?
25,000 - 63,000
The presence of ice pellets at the surface is evidence that there is…
a temperature inversion with freezing rain at higher alt.
What conditions are associated with a cold front?
As the cold front passes towering cumulus or cumulonimbus clouds tower. Depending on intensity, heavy rain, lightning, thunder and or hail. Visibility is poor, winds gusty, dew point drops.
What conditions are associated with an occluded front?
An occluded front is when a fast moving cold front catches a slow moving warm front. As the occluded front approaches warm front weather prevails but is immediately followed by cold front weather. Embedded t-storms, rain fog are associated with this front.
The most hazardous conditions for icing are a result of what weather conditions?
Freezing Rain
(formed from SLD {Supercooled Large Drops})
What are some characteristics of a high pressure system?
High pressure systems are generally areas of dry, descending air. Favorable weather is typically associated with high pressure systems.
Name and describe 3 principle thunderstorms types.
Single cell thunderstorms- Consists of 1 cell. Rare and easily circumnavigated.
Multicell cluster t-storms- Consists of a cluster of cells at various stages. Lifespan of several hours.
Supercell t-storms- Often dangerous convective storm that consists of a single quasi-steady rotating updraft that persists. Updraft speeds of 9000 ft/min (100 knots). Produce severe weather.
What 3 conditions are needed for thunderstorms to develop.
Water vapor, lifting action, unstable air.
