Earth Science Chapter 20


Terms in this set (...)

Air Mass
A huge body of air that has similar temperature, humidity, and air pressure at any given height
A boundary between two air masses
Warm Front
a front where warm air moves over cold air and brings drizzly rain and then are followed by warm and clear weather
Cold Front
forms when cold air moves under warm air which is less dense and pushes air up (produces thunderstorms heavy rain or snow
Stationary Front
A boundary between air masses that don't move possibly causing rain for several days
Occluded Front
a front where a warm air mass is caught between two colder air masses and brings cool temperatures and large amounts of rain and snow
a strong storm with a lot of rain, thunder, and lightning
A destructive, rotating column of air that has very high wind speeds and that may be visible as a funnel-shaped cloud
A severe storm that develops over tropical oceans and whose strong winds of more than 120 km/h spiral in toward the intensely low-pressure storm center
Eye Wall
the area immediately outside the eye of a hurricane or cyclone, associated with tall clouds, heavy rainfall, and high winds.
Zone of a hurricane where precipitation ceases and winds become less strong
Storm Surge
a rising of the sea as a result of atmospheric pressure changes and wind associated with a storm.
Lake Effect snow
This is cased by the large contrast in temperatures b/t the lake water and air mass moving over it. When the air mass reaches the other side of the lake, it is humid and unstable which leads to heavy snow.
Formation of a mid latitude cyclone
A) Stationary front forms as 2 air masses with different temperatures move in opposite directions
B) The front takes on a wave shape (100's of km long)
C) Changes in airflow and pressure result in counterclockwise flow of air
D) An occluded front begins to form (cold front lifts the warm front)
E) Occluded front is formed
F) Once most warm air is forced up and displaced, cyclone weaken
Mid latitude cyclone
Large centers of low pressure that generally travel from west to east to cause stormy weather.
Air moves counter clockwise and inward
Airflow aloft
high in the air, above surface flows/cyclones
Usually airflow aloft ______ a middle-latitude cyclone
outward, inward
As long as the ________ flow of air aloft is greater than or equal to the ________ surface flow, then the low-pressure system can be sustained.
anticyclones feed _______
continental polar
maritime polar
continental tropical
maritime tropical
Most thunder storms occur in the _____
Cumulus stage
Updrafts of warm, moist air cause the vertical development of the thunderstorm cloud
Mature stage
Heavy precipitation, lightning, gusty winds, sometimes hail
Dissipating stage
Downdrafts of cool air and cooling effect of precipitation cause storm to die down
Water Vapor
Hurricanes form when huge quantities of ______ condense
Most often develop in late summer when water temperatures are warm enough to provide the necessary heat and moisture to the air
______ Pressure center = good weather
______ Pressure center = bad weather.
An air mass can be as big as ____ km across and 7 km thick
Source region
area over which an air mass gets its characteristics
Lake effect snow
cP air masses are not associated with precipitation except ____________
mP air masses can lead to cold stormy storms called a _____
A Nor'Easter happens when north eastern U.S. is just north of a low pressure center which has ______ winds