Final answer:
Thunderstorm frequency is influenced by the rain shadow effect of mountains, with storms typically being more frequent on the windward side. Thunderstorms in the eastern U.S. increase in frequency from north to south due to warmer and more humid conditions in southern regions, with future changes in storm patterns expected due to climate change.
Step-by-step explanation:
The relationship between thunderstorm frequency and mountainous terrain is influenced by the rain shadow effect. This occurs when mountains block the passage of precipitation-bearing clouds, causing one side to receive abundant rainfall while the other side remains dry. This effect is evident in areas with high elevation, including the Pacific Mountains and Valleys and the Rocky Mountains.
As for the frequency of thunderstorms from north to south over the eastern half of the nation, it generally increases as you move southward. This is because southern areas tend to be warmer and more humid, which are favorable conditions for thunderstorm development. Climate changes are projected to affect precipitation patterns and storm events, which may lead to regional variations in thunderstorm frequency.
Future precipitation trends suggest that while some regions may experience an increase in precipitation and storm activity, including heavier rainfall during events, others may see a decrease. Overall, thunderstorm patterns over the United States are expected to be influenced by these changing climate conditions and may also be affected by the strength of tropical storms and barometric pressure differences.