Earth Science, Tarbuck Chap 19 Flashcards
What are air masses
large bodies of air that have uniform temperature and moisture across a given altitude
How are air masses categorized
Polar(high latitude, cold), Arctic(high latitude, cold), tropical(low latitude, warm), continental(origin above continent, dry) and maritime(origin above Water, humid)
What are lake effect snows
When cP air masses move over across a lake in winter months, the warmth and moisture of a lake causes clouds to develop
where do cP air masses form that affect America
Canada, air masses move southward
Where do mT air masses form that affect America
Gulf of Mexico, move Northward
maritime tropical air masses have what effect on america
produces most of the precipitation in America
Air mass that least affects American weather
Continental Tropical
What is a Nor’ Easter
Storm along East Coast of America originating from North East, most often England. Occurs in winter and is caused by Cyclone pulling in maritime polar air as it travels across the atlantic
What are fronts
boundary surfaces that
separate air masses of different densities
What is Overrunning
Warm air masses rise above cold ones in fronts
What is a warm front
surface position of a front moves so that warm air
occupies territory formerly covered by cooler air,
Warm fronts bring what
Precipitation
When warm fronts approach, what clouds form
Cirrus -> Cirrostratus -> stratus -> nimbostratus ->
What precipitation does warm fronts bring
Light-moderate precipitation over extended periods
What temperature difference does warm fronts bring
Gradual increase in temperature
What is a cold front
When dense cold air is actively advancing into a region
occupied by warmer air
Cold front weather is usually what
violent
As cold fronts approach, what clouds form
dark band of ominous clouds
Precipitation formed in cold fronts
Violent storms but for small durations
What is a stationary front
flow on both sides of a front is neither toward the cold air mass nor toward the warm air mass but almost parallel to the line of the front
What is an occluded front
forms when a warm air mass gets caught between two cold air masses
Primary Weather producers in Mid-latitude
Mid-latitude cyclones
What are Mid-Latitude Cyclones
large centers of low pressure that generally travel from west to east. Forms when contrasting air masses, typically cold polar air mass and a warm tropical air mass,
Weather in mid-latitude cyclones
Abundent precipitation
Shape of Mid-latitude Cyclone
Comma shaped
What are tornados
narrow, violently rotating column of air that extends from a thunderstorm to the ground. The tornado has very low pressure compared to surrounding air, which causes the insurgence of air
Stronger tornadoes oftenly contain what
Smaller vortices within the large one, called suction vortices
What are supercells
Huge thunderstorms
What is needed to create a thunderstorm
Moisture, instability, and lifting mechanism
What is wind shear
a wind direction and/or speed change over a vertical or horizontal distance
What is a mesocyclone
a vertical
cylinder of rotating air, typically about 3 to 10 kilometers
(2 to 6 miles) across, that develops in the updraft of a
severe thunderstorm.
How do mesocyclones form
Speed wind shear(Wind gets faster as elevation increases due to less friction) causes wind to produce a rolling motion. If updraft causes this rotating air to be aligned nearly vertical, a mesocyclone forms, producing a wall cloud.
How are Tornadoes and mesocyclones related
Mesocyclones generate a wall cloud( a large, rotating, localized cloud that forms beneath a thunderstorm base) where a funnel cloud emerges. If the funnel clouds touches the ground, a tornado is formed
Why do mid-latitude cyclones form around Central America
no significant natural barrier separating the center of the country from the arctic or the Gulf of Mexico
Where do the air masses that form mid-latitude cyclones usually originate in america
polar air from Canada and maritime tropical air from the Gulf of
Mexico
The greater the contrast between the two air masses, the greater the
Intensity of the storm
Most commonly used guide to tornado intensity
Enhanced Fujita intensity scale
How does the enhanced fujita intensity scale work
by assessing the worst damage produced by a
storm, taking account of structural integrity of buildings
What are hurricanes
are intense centers of low pressure
what form over tropical oceans and are characterized by
intense thunderstorm activity
Difference between Mid-latitude cyclones and Hurricanes
Hurricanes do not have contrasting air masses and fronts
What energy maintains the hurricane
huge quantity of latent heat liberated during the formation of the storm’s cumulonimbus towers
How is the pressure gradient from the outer to the inner edge of a hurricane
Steep, inner edge of hurricane is very low pressure
What is the eye wall in a hurricane
doughnut-shaped wall of intense convective activity surrounding the center of the storm
Where does the heaviest rainfall and the highest wind speed occur in a hurricane
Eye wall
What is at the center of a hurricane
Hurricane eye, where wind and rain subsides
When do most hurricanes form
Summer, where water temperatures are above 80 F
Where do most hurricanes form
5-20 degree latitude
Why do hurricanes not form from the equator to 5 degrees latitude
Coriolis effect is too weak to initiate rotary motion
How do hurricanes decay
Move onto land, Move into areas without warm, moist air, or move into location where flow aloft is not favorable
What is the Main Hurricane scale we use
Saffir-Simpson Scale
