CK12 Earth Science

If the air mass is very different from the ground beneath it, storms may form. For example, when a colder air mass moves overwar ...

of fronts move in the Southern Hemisphere is the mirror image of how they move in the Northern Hemisphere. Fronts can be slowed ...

Figure 16.16: A cold front with cold air advancing to displace warm air. The warm air is pushed up over the cold air. ( 30 ) Fig ...

Imagine that you are standing in one spot as a cold front approaches. Along the cold front, the denser, cold air pushes up the w ...

Imagine that you are on the ground in the wintertime under a cold winter air mass with a warm front approaching. The transition ...

Occluded Front Anoccluded frontorocclusion( 4 ) usually forms around a low pressure system (Figure 16.20). The occlusion starts ...

At a cold front, a cold air mass takes the place of a warm air mass and forces the warm air upwards. The opposite occurs at a w ...

occluded front A front in which a cold front overtakes a warm front. squall line A line of thunderstorms that forms at the edge ...

Thunderstorms Thunderstormsare extremely common. Across the globe, there are about 14 million per year; that’s 40,000 per day! M ...

At the top of the stratosphere, upper level winds blow the cloud top sideways to make the anvil shape that characterizes a cloud ...

Figure 16.23: A mature thunderstorm showing updrafts and downdrafts that reach the ground. This thunderstorm will no longer grow ...

than 15 kilometers (50,000 feet). In the United States, squall lines form in spring and early summer where the maritime tropical ...

5,000 feet or about 1 mile (1,650 m) away. Thunderstorms kill approximately 200 people in the United States and injure about 550 ...

Figure 16.26: The formation of this tornado outside Dimmit, Texas in 1995 was well studied. ( 10 ) ...

Tornadoes strike a small area compared to other violent storms, but they can destroy ev- erything in their path. Tornadoes uproo ...

Figure 16.29: The frequency of F3, F4 and F5 tornadoes in the United States. The red region that starts in Texas and covers Okla ...

Table 16.3: (continued) F Scale (km/hr) (mph) Damage F4 333-419 207-260 Devastating - houses leveled, cars thrown F5 420-512 261 ...

Figure16.30: Ahypotheticalmid-latitudecycloneaffectingtheUnitedKingdom. Thearrows indicate the wind direction and its relative t ...

Figure 16.31: The 1993 “Storm of the Century” was a nor’easter that covered the entire eastern seaboard of the United States. ( ...

arise in the tropical latitudes (between 10oand 25oN) in summer and autumn. The warm seas create a large humid air mass. The war ...