Thunderstorms
Thunderstormsare extremely common. Across the globe, there are about 14 million per
year; that’s 40,000 per day! Most come and go quickly, dropping a lot of rain on a small
area, but some are severe and highly damaging. Thunderstorms are most common when
ground temperatures are high. This tends to be in the late afternoon or early evening in
spring and summer. As temperatures increase, warm, moist air rises. These updrafts form
first cumulus and then cumulonimbus clouds (Figure16.21).
Figure 16.21: On a warm spring or summer day, air warmed near the ground rises and forms
cumulus clouds. If warm air continues to rise, cumulonimbus clouds form. ( 19 )