What is the coldest layer of the atmosphere

As the mesosphere extends upward above the stratosphere, temperatures decrease. The coldest parts of our atmosphere are located in this layer and can reach –90°C. In the forth layer from Earth's surface, the thermosphere, the air is thin, meaning that there are far fewer air molecules.

Answer feldspar,quartz,mica and amphibole;

Answer mauritania is in the northwestern part of african, meaning its in the western hemisphere, and how do i know/ the map showed me so; ///: )