Final answer:
The troposphere is the lowest atmospheric layer, ranging up to about 11-13 km, with weather phenomena, greenhouse effects, and a temperature decrease with altitude. It contains most of the Earth's atmospheric mass and is composed mostly of nitrogen and oxygen.
Step-by-step explanation:
Characteristics of the Troposphere
The troposphere is the lowest layer of Earth's atmosphere and has several distinct characteristics. It extends from the Earth's surface up to an altitude of about 11-13 km (7-8 miles), but it can reach up to 15 km in the tropics. Within this layer, the temperature decreases with increasing altitude, with values near 50 °C below freezing at the upper boundary known as the tropopause, marking the transition to the stratosphere. Most atmospheric wind and weather phenomena, including the formation of clouds and precipitation, occur within the troposphere. It is also the part of the atmosphere that contributes to the greenhouse effect due to the trapping of heat by gases like carbon dioxide and water vapor. The troposphere contains approximately 80% of the Earth's atmosphere by mass.
Additionally, the characteristic of temperature decrease with altitude is due to the heating of the atmosphere from the surface upward, with the Sun warming the Earth's surface, and in turn, the surface radiating heat into the atmosphere. This creates convection currents that result in weather patterns and cloud formation. The troposphere is denser than the layers above because of the gravitational pull on the gases closer to Earth's surface, and it is composed primarily of nitrogen (about 78.1%) and oxygen (about 21.0%), with other gases making up the remaining composition.