Thunderstorms, with their jagged bursts of lightning and roaring thunder, are actually one of nature’s primary mechanisms for transferring heat from the surface of the earth into the atmosphere. A thunderstorm starts when low-lying pockets of warm air from the surface of the earth begin to rise. The pockets of warm air float upward through the air above that is both cooler and heavier. The rising pockets cool as their pressure decreases, and their latent heat is released above the condensation line through the formation of cumulus clouds.

   What will happen with these clouds depends on the temperature of the atmosphere. In winter, the air temperature differential between higher and lower altitudes is not extremely great, and the temperature of the rising air mass drops more slowly. During these colder months, the atmosphere, therefore, tends to remain rather stable. In summer, however, when there is a high accumulation of heat near the earth’s surface, in direct contrast to the considerably colder air higher up, the temperature differential between higher and lower altitudes is much more pronounced. As warm air rises in this type of environment, the temperature drops much more rapidly than it does in winter; when the temperature drops more than 4 degrees Fahrenheit per thousand feet of altitude, cumulus clouds aggregate into a single massive cumulonimbus cloud, or thunderhead.

   In isolation, a single thunderstorm is an impressive but fairly benign way for Mother Earth to defuse trapped heat from her surface; thunderstorms, however, can appear in concert, and the resulting show, while extremely impressive, can also prove extraordinarily destructive. When there is a large-scale collision between cold air and warm air masses during the summer months, a squall line, or series of thunderheads, may develop. It is common for a squall line to begin when an advancing cold front meets up with and forces itself under a layer of warm and moist air, creating a line of thunderstorms that races forward at speeds of approximately forty miles per hour. A squall line, which can be hundreds of miles long and can contain fifty distinct thunderheads, is a magnificent force of nature with incredible potential for destruction. Within the squall line, often near its southern end, can be found supercells, long-lived rotating storms of exceptional strength that serve as the source of tornadoes.

It can be inferred from the passage that, in summer, ________.

Câu hỏi liên quan

• According to the passage, what causes the unique color and look of hummingbirds?

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ZUNIA12

• According to the passage, the doers of education are .............

• The changes possibly caused by the cellphones are mainly concerned with ______.

• Using the information in paragraph 2 as a guide, it can be inferred that ...............

• In the passage, the expression “children interrupt their education to go to school” mostly implies that ..........

• According to the passage, Moby Dick is .............

• Nowadays there are ____________.

• The word “flawed” in line 14 is closest in meaning to .............

• According to the passage, what does “slip away” mean?

• The phrase “reach to the horizon” in paragraph 4 is closest in meaning to ______.

• All of the following are mentioned in the passage about supercells EXCEPT that they ________.

• Where in the passage is the name of Pippin’s hometown mentioned?

• According to paragraph 1, the author of the passage argues that ................

• According to the passage, the difficulty in diagnosing allergies to foods is due to ______________.

• Which of the following statement is TRUE about the passage?

• Why does the author mention “the gold and silver rushes of the 1850's and 1860's” in the first paragraph?

• The word "These" in paragraph 3 refers to ..........

• According to the passage, to learn new information, low-achieving students do NOT .............