Weather occurs mainly in the troposphere, which is the lowest layer of Earth's atmosphere. This layer extends from the surface of the Earth up to about 8 to 15 kilometers (5 to 9 miles) high, depending on where you are on Earth.
Weather happens in the troposphere because it contains most of the atmosphere's mass and the majority of its water vapor. This water vapor is crucial for forming clouds and precipitation. The troposphere is also where temperature changes can lead to air movement and create wind patterns, which are essential for the development of various weather phenomena like storms, rain, and sunshine.