What is the name of the lowest layer of the atmosphere?

The lowest layer of the atmosphere is known as the troposphere. This layer extends from the Earth's surface up to about 8 to 15 kilometers, depending on geographic location and weather conditions. The troposphere is where we experience most weather phenomena, such as clouds, rain, and storms. It contains approximately 75% of the atmosphere's mass and is characterized by a decrease in temperature with altitude. This layer is critical for aviation, as it influences flight operations due to turbulence, weather patterns, and air density.