How are monsoons different at different times of the year?
Monsoons are simply changes in direction of the flow of humidity. In North America, this occurs in around June as the Gulf of Mexico and Caribbean Sea warm up and push toward the southwestern states. This causes the normally arid southwestern deserts to become very humid and thunderstorms are the result. The Asian monsoons occur in around September, when the reduced temperatures in the Asian deserts as fall approaches creates a vacuum and causes moisture from the Indian Ocean to be sucked up into the normally dry Asian continent. This combined with the cooler air over the deserts results in thunderstorms and flooding of the Asian continent. Monsoonal conditions occur on all of the continents except Antarctica, at different times of the year and for different reasons. But, the key is the migration of large masses of moist air into regions that are otherwise fairly dry.
