Chapter 19 Vocabulary

Question 1

air mass

Answer 1

large body of air 1000 miles or more across and several kilometers thick characterized by a similarity of temperature and moisture at any given altitude

Question 2

mT, mP, cT, & cP- m

Answer 2

maritime, continental, tropical, polar

Question 3

lake-effect snows

Answer 3

cP air mass that produces heavy snow downwind of large bodies of water. In the fall, lakes represent heat reservoirs and dump snow on leeward shores. (Snowbelt) around Great Lakes

Question 4

What is the source of most precipitation in the eastern 2/3 of the U.S.?

Answer 4

Gulf Air

Question 5

front

Answer 5

boundary surfaces that separate air masses of different densities one warmer and often higher in moisture than the other in a 15-200 km (9-120 mi.) band. Most air masses maintain their identity and have little mixing because of differing densities

Question 6

What are characteristics of a warm front?

Answer 6

warm air occupying territory formerly covered by cooler air. As warm air advances up along the retreating tail of cold air the air rises and cools adiabatically and forms characteristic cloud and precipitation patterns. Warm fronts usually produce moderate to gentle precipitation and a gradual increase in temp. Winds may shift from the E to SW

Question 7

overrunning

Answer 7

warm air moving up the slope of cold air

Question 8

What are the characteristics of a cold front?

Answer 8

steeper slope and faster movement. May have marked temperature drop and wind shift from S to W or NW. Weather is dominated by subsiding and relatively cold air mass hence clearing conditions prevail after the frontal passage

Question 9

Stationary front

Answer 9

either warm or cold fronts in which there is little movement over a 24 hr. period. May produce large amounts of precipitation

Question 10

occluded front

Answer 10

active cold front overtakes a warm front. The cold front wedges the warm air up away from the earth causing complex weather and often precipitation

Question 11

Describe thunderstorm formation.

Answer 11

require warm, moist air that when lifted releases its latent heat, becomes
unstable and rises. High surface temperatures aid in formation and storms are most common in afternoon and evening

Question 12

lightning

Answer 12

differential charge buildup in clouds and the ground

Question 13

thunder

Answer 13

explosive expansion of air heated to extremely high

temperatures, as much as 33,000 degrees celsius

Question 14

mesocyclone

Answer 14

vertical cylinder of rotating air 2-6 miles in diameter that develops in the updraft of a
severe thunderstorm. Formation of this large vortex precedes tornado formation by as much as 30 minutes. About half of all mesocyclones produce tornadoes

Question 15

What are the conditions for tornado formation?

Answer 15

warm moist low level jet of mT air; W to E upper level jet; large temperature contrast between warm and cold air; and rapidly moving cold front usually with squall lines

Question 16

What are the conditions for hurricane formation?

Answer 16

Tropical cyclones with wind speeds reaching 186 mph and extending several hundred miles in diameter. Formed between 5 and 20 deg. of equator and have min. wind speed of 74 mph. and a rotary circulation. Powered by the latent heat released by tropical moisture taken aloft. Sea temperatures usually over 80 F. It is a way of carrying excess heat energy to polar regions

Question 17

storm surge

Answer 17

dome of water 40-50 miles long that sweeps the coast near the point where the eye makes landfall. It has superimposed on it the high waves associated with hurricanes and the surge is responsible for most of the deaths from hurricanes