Weather patterns on Earth are driven by the unequal heating of the surface by sunlight. The Sun is the ultimate source of energy that drives wind, rain and storms across the planet. The movement of wind patterns, ocean currents and even the water cycle can all be thought of as global mechanisms for redistributing heat from the Sun.
As sunlight reaches the Earth, it imparts its energy to the planet, warming it. Some places on Earth, however, are better than others at absorbing the Sun's energy. Ice, for example, reflects around 90 percent of the sunlight that hits it. Seawater, however, absorbs around 90 percent of received sunlight. Deserts and clouds tend to be reflective and difficult to heat, while forests and grasslands tend to be dark and heat absorbent.
As heat is applied unevenly across the globe, thermal differentials begin to form along with pressure gradients. Generally, high-pressure air rushes to equalize with nearby areas of low-pressure air, and high-temperature areas bleed heat into cooler areas nearby. The rushing back and forth of air carries clouds with it and can be felt as wind. Under certain conditions, the confluence of pressure, temperature and humidity can trigger storms, temperature inversions and every other phenomenon associated with weather.