Why lightning occurs only on rainy seasons?

Lightning begins as static charges in a rain cloud. Winds inside the cloud are very turbulent. ... These electrical fields become incredibly strong, with the atmosphere acting as an insulator between them in the cloud. When the strength of the charge overpowers the insulating properties of the atmosphere, Z-Z-Z-ZAP!

Explanation:

i would expect light rain in pittsburgh throughout the following 24 to 48 hours. the lower/falling weights in urban areas toward the west demonstrate that a low weight framework is moving from west to east toward pittsburgh. low weight frameworks are ordinarily connected with precipitation. the way that you don't see a major drop in temperature in the more western urban areas demonstrates the low weight framework is moving with a warm front, so just light rain would be normal. substantial downpours or progressively vicious climate is just typically connected with chilly fronts, where the warm air is pushed up and over a cool front quickly. this quickly rising air (convection) is what gives you heavier torrential downpours, and other conceivably serious weather conditions.