Weather is the day-to-day changes in temperature, air pressure, moisture, wind, cloudiness, rainfall and sunshine. Such changes arise from the movement of air in the Earth's atmosphere and the accompanying transfers of heat and moisture. This heat and moisture transport generates the weather features and systems which we see and experience, including clouds, fronts, depressions and anticyclones.
Click Bart Simpson (left) for the easy-to-read young person's text and Mr. Burns (right) for the more technical information.