The troposphere is characterized by a decrease in temperature with increasing altitude. This occurs because the troposphere is heated from the Earth's surface, causing warm air to rise and cool as it gets higher. The boundary between the troposphere and the layer above it, the stratosphere, is called the tropopause.
The troposphere is crucial for supporting life on Earth and plays a significant role in regulating the planet's climate. It is also where most of the atmospheric pollutants and greenhouse gases are found, which can have direct impacts on air quality and climate change.