Chapter 20 Flashcards
What is a huge body of air in the troposphere with similar temperature and humidity throughout?
An air mass
Which thing on a station model gives two pieces of info?
Wind gives speed and direction
What is an area that an air mass took on the temperature and humidity of?
A source region
What can a source region be?
Land or water
Are source regions windy places?
NO
Continental
Low humidity (land)
Maritime
High humidity (oceans)
Polar
Cool/cold
Tropical
Warm
What is formed when two different air masses meet?
A front
What is it when the colliding air masses stop moving, or move parallel to the front between them, the front itself doesn’t move over the ground?
A stationary front
What forms if a warm air mass overtakes a cold air mass?
Warm front
What happens when a cold air mass meets a warm air mass?
A cold front forms
What do most interaction between air masses cause?
Precipitation
Air is lifted when warm, moist air crosses over a mountain. The mountain forces the air to rise and cool. At the dew point, clouds form and precipitation begins and spills over the other side. What causes this?
Orographic lifting
What causes the collision of horizontal air currents?
Convergence
What are the four types of severe weather?
Winter storms, thunderstorms, tornadoes, and hurricanes
What does hook do?
It indicates the presence of a tornado
What is a Nor’easter?
A cyclonic winter storm
What is a string of thunderstorms along a cold frontal system called?
A squall line
How are thunderheads shaped?
They’re anvil-shaped
What is the air called when a large thunderstorm is approaching and the rain is precede by a blast of noticeably cooler air?
A gust front
What is thunderstorms greatest hazard?
Lightning
What is an electrical discharge either between clouds or between a cloud and the ground?
Lightning
What is a narrow, rapidly spinning mass of air extending downward from a cumulonimbus cloud?
A tornado
What are massive rotating storms?
Supercells
Do tornadoes occur often?
They only occur under unusual circumstances
What are tornadoes associated with?
Supercells
How can you figure how far away lightning is?
By counting the seconds until you hear thunder and divide that number by 5
What are the two great destructive features of a tornado?
The high-speed, rotating wind and the updraft
Are tornado’s path of destruction usually narrow?
YES
What storm has the highest wind speeds?
Tornadoes
Are tornadoes high pressured?
NO
Does pressure cause damage in a tornado?
NO
How high can a tornado’s wind speeds be?
As much as 320 mi/h
What does the Enhanced Fujita-Pearson scale describe?
The width of the destruction path and the distance the tornado was in contact with the ground
Are hurricanes formed by a single cumulonimbus cloud?
NO
Where are hurricanes born?
Within 10-15 degrees latitude of the Equator
What is a cyclonic storm that’s winds reach 39 mi/h or more categorized as?
Tropical storms
How does the speed of the i rushing air increase in a hurricane?
As the low pressure in the center drops, the pressure gradient force grows
What slows hurricanes down?
Land
What are huge waves in hurricanes called?
The storm swell
What is the higher than normal water level called?
The storm surge
What is the storm surge caused by?
Wind
How can you stay safe in a thunderstorm if you’re in an open field?
You crouch down and avoid being the tallest thing around
What does a staff point to?
The direction from which the wind comes
What are lines of equal pressure called?
Isobars
What are the four principle weather maps or charts prepared by the National Weather Service called?
Synoptic weather maps
