One of the most feared occurrences in nature is the tornado. The area most frequently the target of this violent windstorm is the Great Plains, the region extending from the Rockies to the Mississippi, and from Canada down through Texas.
When warm, moist air meets with cooler, drier air at low levels, a tornado often occurs. Prior to the formation of the familiar funnel-shaped cloud, the sky is very clear. Then, a black line suddenly appears. As this black area moves in, the fast wind becomes hot and moist and a deep stillness encircles the landscape. Because the air pressure drops steadily during a tornado, breathing becomes difficult. Insects fall to the ground, unable to balance themselves in flight.
Suddenly, a black funnel resembling a giant whip dips down out of the sky, destroying whatever it touches, and then retreats. Although a tornado usually destroys property rather than lives, an average of 120 people die yearly as a result of these violent storms. It is obvious why the tornado is feared throughout the Great Plains.
Mark the best choice.
1. Before a tornado occurs .
a) there are funnel-shaped clouds in the sky
c) there are cold freezing winds
b) the sky is very dark
d) the sky is cloudless
2. During a tornado, insects .
a) are unable to fly
b) die immediately due to atmospheric pressure
c) breathe at an increasing rate
d) are seldom affected by the heat and moisture
3. As a tornado occurs .
a) hot, dry air encounters cold, damp air
b) air pressure gets progressively lower
c) the black funnel in the sky disappears
d) breathing gets easier
4. Which of the following statements is true?
a) A black line in the sky is a sign that the tornado is over.
b) A tornado is most destructive before the funnel-shaped cloud is formed.
c) The wind is fast, hot and humid during a tornado.
d) Tornadoes are more dangerous for people than for property