The weather changes due to factors like gravity, sunlight, topography, oceans and the movement of air affecting the atmosphere. The atmosphere can be changed through several forces that are both terrestrial and extraterrestrial.
The weather changes with certain conditions in the atmosphere. For example, thunderstorms are created in the same way as clouds are, which is when an air mass rises up and cools, causing water vapor to condense into clouds. However, in the event of the updraft continuing, the cloud will grow and move into the troposphere.
In the midst of a thunderstorm, powerful winds and lightning strikes can evolve into something worse. Tornadoes form from thunderstorms, and they consist of a powerful vortex or several suction vortices that revolve around the center of the tornado.
There are also hurricanes. These storms are low-pressure zones that spin out of the tropics because of the Coriolis effect, which causes them to build up speed and grow to large sizes. As a low-pressure area, the hurricane starts to suck in torrents of surface wind that then moves up into the sky as a column. Within the column, there is a warm air downdraft that fills it, which is commonly called the eye of the hurricane.
These are some of the most extreme cases of the weather conditions, but they are all the direct result of changes in the atmosphere through air pressure, location, temperature and several other factors.