How does the density and temperature change as you move from one layer to another

The atmosphere has 4 layers: the troposphere that we live in near the surface of the earth; the stratosphere that houses the ozone layer; the mesosphere, a colder and lower density layer with about 0.1% of the atmosphere; and the thermosphere, the top layer, where the air is hot but very thin. The structure of the atmosphere dictates the way the atmosphere behaves and controls how weather develops near the surface of the earth. The temperature decreases with height here just like it does in the troposphere. This layer also contains ratios of nitrogen and oxygen similar to the troposphere, except the concentrations are 1000 times less and there is little water vapor there, so the air is too thin for weather to occur. The thermosphere is the uppermost layer of the atmosphere. In this layer the temperature increases with height because it is being directly heated by the sun.

Ghana, first of the great medieval trading empires of western africa (fl. 7th–13th century). it was situated between the sahara and the headwaters of the sénégal and niger rivers, in an area that now comprises southeastern mauritania and part of mali.