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Earth Science Ch 14 Weather Patterns

Terms in this set (41)

What are air masses?
large bodies of air with relatively uniform temperature and moisture properties
What is a source region?
an area of air mass development
What are the Air mass designations?
Latitiude Formation:
--Arctic (A)
--Polar (P)
--Tropical (T)
Surface of Source Area:
--Maritime (m)
--Continental (c)
mT
warm and moist
cP
dry and cold
What are Lake-Effect Snows?
cP air mass travels over Great Lakes and picks up a lot of moisture once over land again, big bands of snows
What is a Nor' Easter?
Low pressure system in Atlantic near New England. Winds come in from North and East bringing cold, moist air. (Snow,etc)
What are Pop-Up Thunderstorms?
mT air mass heats up in afternoon localized rain/thunderstorms
What are Fronts?
the boundary between 2 air masses. Fronts are named based on which air mass is stronger (pushing through)
What are the 4 types of Fronts?
--cold*
--warm*
--occluded
--stationary
What types of clouds arise during a cold front?
cumulonimbus--> heavy rain
Cold air pushes warm air straight up
What types of clouds arise during a warm front?
nimbostratus-->altostratus-->cirrostratus-->cirrus
light to moderate rain for multiple hours
warm air slowly pushes toward cold air, but then goes over top of it
What is a Stationary Front?
air is moving along the boundary, not towards or away from it
What is an Occluded Front?
occurs when a cold front catches up to a leading warm front, lifting all the warm air up and off of the ground
(PURPLE)
What is a Cyclone?
a low pressure system with counter-clockwise winds
What is the first development of a Mid-Latitude Cyclone?
1. A stationary front develops in Pacific NW as mT & cP air masses interact
What is the second development of a Mid-Latitude Cyclone?
2. The stationary front develops a wave
What is the third development of a Mid-Latitude Cyclone?
3. Wind from mT air mass breaches the wave & flows North(ish), cP air mass moves South
*Cyclone flow is established along a central Low pressure zone
What is the fourth development of a Mid-Latitude Cyclone?
4. The cold front moves faster than warm front, & begins to catch up to it near the low pressure center, & zippers its way south along the warm front warm front
What is the fifth development of a Mid-Latitude Cyclone?
5. Storm exhausts itself as occluded front expands down the warm front.
4-6 days to cross America
What are involved in Severe Thunderstorms
--have hail
--damaging winds
--potential for flash flooding
--ground lightning
What must happen to be considered a thunderstorm?
It is a storm that has lightning
What are the sources/locations of most Thunderstorms?
--Along an advancing cold front
--Within mT air masses as "Pop-Up" Thunderstorms
What is hail?
ice falling from the sky
What is hail most associated with?
Tornadoes
What are tornadoes?
Violent windstorm characterized by a vortex (rotating column of air) extends from a cumulonimbus cloud to the ground
What is the maximum size of a tornado?
~ 1 mile across
What is the maximum speed of a tornado?
> 300 mph
What is a suction vortex?
it is like a tornado in a tornado
What are the phases of Tornado Development?
1. supercell
- large t-storm
2. rotation within the cloud
-mesocyclone
3. some fraction of mesocyclones drop to form a tornado
The US average is
>1000 tornadoes/year
the next biggest country for tornadoes
China >100/year
The average tornado is:
500-2,000 ft across
30 mph migration speed
6 miles path on ground
move E/NE ahead of a cold front
What is the Enhanced Fujita Scale?
measures the intensity of a tornado (done after the face, based on damage)
EF0-EF5
Most Injuries are from
flying debris
Where is the Storm Prediction Center located?
Norman, OK
What two things does the Storm Prediction Center do?
-Tornado Watch--> conditions where tornado could form
-Tornado Warning-->rotation of cloud &/or tornado touched down
What can the Doppler Radar do?
It can detect directional movement
What is "Hook Echo"?
signature of rotation within a cloud
What are Hurricanes?
Tropical cyclones with winds greater than 119 km/hr (~74 mph) Strongest storms on the planet.
Also called:
-Hurricanes (Atlantic)
-Cyclones (Indian)
-Typhoons (Pacific)
What are the phases of development for hurricanes?
1) Start as tropical disturbance- water is greater than or equal to 27 degrees centigrade (80 degrees F); disorganized group of storms off of west coast of Africa
2) As system releases heat (via rain), local pressure drops, causing wind to enter towards the lows. Cyclone flow is started;
**Tropical depression- winds of less than or equal to 61 kph (38 mph)
3) The depression strengthens into a tropical storm greater than 61 kph but less than 119 kph (74 mph) gets a name
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