Troposphere

Layer in the atmosphere found from the surface to approximately 11 kilometers of altitude. This layer contains about 75 % of the total mass of the atmosphere. It is also the layer where the majority of our weather occurs. Maximum air temperature occurs near the Earth's surface in this layer. With increasing altitude air temperature drops uniformly with increasing height at an average rate of 6.5 degrees Celsius per 1000 meters (commonly called the Environmental Lapse Rate), until an average temperature of -55 degrees Celsius is reached at the top of the troposphere.