Exam 14: Thunderstorms

The greatest frequency of hailstorms in the United States is ____.

What is a microburst? Why do microbursts represent a hazard to aviation?

Sonic booms are produced when an aircraft exceeds the speed of light at the altitude at which it is flying. The aircraft compresses the air, forming a shock wave that trails out as a cone behind the aircraft. Along the shock wave, the air pressure changes rapidly over a short distance. The rapid pressure change causes the distinct boom.

A sound occasionally mistaken for thunder is the ____________________.

How do downdrafts form in ordinary cell thunderstorms?

Ordinary cell thunderstorms most frequently form ____.

For ____ to occur, separate regions containing opposite electrical charges must exist within a cumulonimbus cloud.

When convection is strong and the updraft intense, the rising air may intrude into the stratosphere, producing ____.

The wind shear associated with several major airline crashes is believed to have been caused by ____.

Many flash floods, including the one that occurred in Colorado's Big Thompson Canyon, are the result of thunderstorms that _____.

It is estimated that more than ____ thunderstorms occur each day throughout the world.

Positive lightning has the potential to cause more damage because it generates a much higher current level and its flash lasts for a longer duration than negative lightning.

One theory of cloud electrification states that during the formation of precipitation, regions of separate charge exist within tiny cloud droplets and larger precipitation particles. In the lower part of these particles we find negative charge, whereas in the upper part we find positive charge.

Positive lightning is more common with ____ thunderstorms.

Where do thunderstorms form most frequently in the United States? Why is this the case?

Describe one process by which thunderstorms become electrified.

An ordinary thunderstorm ____.

In the valleys of central and southern California, dry, sinking air produces an inversion that inhibits the development of towering cumulus clouds during the summer. Hence, in these regions, thunderstorms are most frequent in winter and spring, particularly when cold, moist, conditionally unstable air aloft moves over moist, mild surface air.

Downdrafts tend to dominate during the ____ stage.

Sinking air warms, yet the downdrafts in a thunderstorm are usually cold.