Elements of Weather

Dr. Czarnetzki

Chapter 10

Review Questions

2. The term cyclone refers to any low pressure center, not just to severe storms like tornadoes and hurricanes. In its most general sense, it refers to any feature that rotates in the same direction as the earth, which depends on the hemisphere you’re in, right?

3. Tornadoes are the smallest (1/4 mile in diameter) and most short-lived of the three phenomena and produce the strongest winds on earth. Middle latitude cyclones are the largest of the three (1600 km or more in diameter) and have the least violent winds. Averaging 600 km across, hurricanes are much larger and longer-lived than tornadoes but are smaller than middle latitude cyclones. To be classified as a hurricane, wind speeds must be at least 115 km per hour.

5. Lightning and flash floods.

7. In the tropics, where the general convergence associated with the Intertropical Convergence Zone and warm, moist unstable air combine to make conditions right for thunderstorm development. In the United States, the Gulf Coast and Florida experience the greatest amount of thunderstorm activity because this area is closest to the source region of mT air masses.

10. The electrical discharge of lightning heats the air and causes it to expand explosively. The expansion produces the sound waves that we hear as thunder.

11. Heat lightning (lightning seen without any accompanying thunder) is simply ordinary lightning that occurs more than 20 km away from the observer. At this distance, the sound energy dissipates before reaching the observer or is refracted over the observer's head.

18. A tornado watch alerts the public to the fact that conditions are right for the formation of tornadoes, while a tornado warning is issued when a tornado has actually been sighted in an area or is indicated by radar. A major difficulty in tornado prediction is that observation sites are too sparse to describe atmospheric variability on the scale producing the tornado. Thus, even if our knowledge of tornado formation were adequate, the current observing network is a limiting factor.

19. Higher at point B; Doppler effect.


1. About 3 miles.