Question 1

If you see lightning and then, 15 seconds later, hear the thunder, the lightning stroke is about ____ miles away.

Accepted Answer

Sound travels approximately one mile in five seconds. If you hear thunder 15 seconds after seeing lightning, the lightning is about 3 miles away (15 seconds divided by 5 seconds per mile).

Question 2

A relatively narrow downburst, less than four kilometers wide, is called a ____.

Accepted Answer

A downburst less than four kilometers wide is considered a microburst. Macrobursts are larger than four kilometers in diameter. Funnel clouds are rotating columns of air that extend from the base of a thunderstorm but do not reach the ground. Mesocyclones are rotating updrafts that are associated with supercell thunderstorms.

Question 3

What weather system can grow to be as much as 1000 times larger in area than an ordinary cell thunderstorm, even large enough to cover an entire state?

Accepted Answer

Mesoscale convective complexes (MCCs) are large clusters of thunderstorms that can grow to be as much as 1000 times larger in area than an ordinary cell thunderstorm, even large enough to cover an entire state. Overshooting thunderstorms and mesocyclones are specific types of thunderstorms that can be part of an MCC, but they do not describe the entire system. Derechos are also related to thunderstorms, but they are characterized by strong, straight-line winds and a specific pattern of damage rather than their size.

Question 4

Beneath an intense thunderstorm, the downdraft may become localized so that it hits the ground and spreads horizontally in a radial burst of wind. This is called a ____.

Accepted Answer

A downburst is a strong ground-level wind system that emanates from a point above and spreads outwards upon hitting the ground, typically associated with intense thunderstorms.

Question 5

Thunder is caused by ____.

Accepted Answer

Thunder is caused by the rapid heating of air surrounding a lightning channel. When lightning strikes, it heats up the air around it to temperatures that are hotter than the surface of the sun. This causes the air to rapidly expand, creating a shockwave that we hear as thunder.

Question 6

An ordinary cell thunderstorm is a ____.

Accepted Answer

An ordinary cell thunderstorm is a scattered or isolated storm that is not severe. It can produce lightning, thunder, and small hail, but is not usually associated with large hail, tornadoes, or damaging winds.

Question 7

Ordinary cell thunderstorms only last about one hour and begin to dissipate when ____.

Accepted Answer

When the downdraft in the cell thunderstorm spreads throughout the cloud and cuts off the updraft, the storm begins to dissipate. This is because the updraft is what drives the storm, and without it, the storm cannot sustain itself. The other options do not accurately describe the end of a cell thunderstorm.

Question 8

The initial stage of an ordinary cell thunderstorm is the ____.

Accepted Answer

The cumulus stage is the first stage of an ordinary cell thunderstorm, characterized by the development of tall, vertically growing cumulus clouds due to the upward movement of warm, moist air.

Question 9

A small thunderstorm cloud blowing dust at the ground could warn of a severe hazard to aircraft. Why?

Accepted Answer

A small thunderstorm cloud blowing dust at the ground could indicate the presence of an intense downdraft or microburst, which can cause rapid changes in wind speed and direction that can be extremely hazardous to aircraft.

Question 10

What would you expect to observe during the passage of a gust front?

Accepted Answer

A gust front is the leading edge of a thunderstorm's outflow. As it moves over an area, it brings in cool air which drops the temperature. The gust front also causes a sudden shift in wind direction and increase in wind speed, creating strong and gusty winds. Therefore, the correct observation during the passage of a gust front would be temperatures dropping and winds becoming strong and gusty.

Question 11

A line of thunderstorms that forms ahead of an advancing cold front is called a ____.

Accepted Answer

A line of thunderstorms that forms ahead of an advancing cold front is called a squall line.

Question 12

A group of thunderstorms that develop next to one another, each in a different stage of development, is called a(n) ____.

Accepted Answer

A multicell thunderstorm is a group of thunderstorms that develop next to one another, each in a different stage of development.

Question 13

Many flash floods, including those that occurred over parts of New England and the mid-Atlantic states during June 2006, and in Colorado's Big Thompson Canyon in July 1976, are the result of thunderstorms that ____.

Accepted Answer

Flash floods caused by thunderstorms result from a large amount of rainfall in a short period of time. Thunderstorms that move slowly have more time to deposit excessive rainfall in one area, leading to flash flooding. Thunderstorms with weak or non-existent downdrafts can also contribute to flash flooding as the rain is not pulled down to the ground as quickly, allowing it to accumulate and potentially cause flooding. However, the presence or absence of lightning and the surrounding air mass do not necessarily contribute to the formation of flash floods caused by thunderstorms.

Question 14

The majority of lightning strikes occur ____.

Accepted Answer

The majority of lightning strikes occur within a cloud, as the electrical charges within the cloud seek to balance themselves. This is more common than strikes between clouds or from clouds to the ground.

Question 15

The greatest annual number of thunderstorms in the United States occurs in ____.

Accepted Answer

Florida is known as the thunderstorm capital of the United States, with an average of 100 thunderstorm days per year.

Question 16

Occasionally, an elongated ominous-looking cloud forms just behind a gust front. This type of cloud, which appears to slowly spin about a horizontal axis, is called a ____.

Accepted Answer

The description matches that of a roll cloud, which forms along the leading edge of a cool outflow from a thunderstorm and has a distinct rolling motion. A downburst is a strong downdraft that can cause damaging surface winds. A shelf cloud is a low, horizontal cloud that forms along the leading edge of a thunderstorm and often indicates strong winds. A wall cloud is a vertical, funnel-shaped cloud that forms beneath a cumulonimbus cloud in a thunderstorm and can indicate the potential for tornado development.

Question 17

A supercell storm is a(n) ____.

Accepted Answer

A supercell storm is characterized by a single rotating updraft, which distinguishes it from a multicell thunderstorm in which the rotating updraft is usually separated into multiple cells.

Question 18

The leading edge of a thunderstorm's cold outflowing air is known as a ____.

Accepted Answer

The leading edge of a thunderstorm's cold outflowing air is known as a gust front.

Question 19

The downdraft in an ordinary cell thunderstorm is created mainly by ____.

Accepted Answer

The downdraft in an ordinary cell thunderstorm is primarily caused by evaporating raindrops, which cool the air. This cooler air becomes denser and heavier, leading to a downward movement or downdraft.

Question 20

The top of a thunderstorm is normally ____ charged, and the middle and lower parts are ____ charged.

Accepted Answer

The top of a thunderstorm is normally positively charged, while the middle and lower parts are negatively charged. This is due to the separation of charged particles within the storm, with positive charges accumulating at the top and negative charges accumulating at the bottom.

Quiz 10: Thunderstorms and Tornadoes