What is the first layer of the atmosphere closest to Earth called?

The first layer of the atmosphere closest to Earth is known as the troposphere. This is the layer where all weather events occur, and it contains about 75% of the atmosphere's mass, including most of its water vapor and aerosols. The troposphere extends from the Earth's surface up to about 8 to 15 kilometers (5 to 9 miles) high, depending on the location, with the height varying between the equator and the poles.

In the troposphere, temperature generally decreases with increasing altitude, which leads to the formation of clouds and a variety of weather phenomena. This layer is crucial for life on Earth, as it supplies the air we breathe and regulates weather patterns. Understanding the composition and functions of the troposphere helps to appreciate its role in the larger context of Earth's atmosphere and climate systems.

The other layers of the atmosphere, such as the stratosphere, mesosphere, and exosphere, lie above the troposphere and have distinct characteristics and functions that set them apart from the troposphere.