Identify the coldest region among the following layers of atmosphere?

The coldest region among the Mesosphere layers of atmosphere. It is the layer present between the stratosphere and te thermosphere. It has the area between the $50 \mathrm{to} 85 \mathrm{km}$. It has the temperature of the $-90{ }^0\mathrm{C}$.

Hence, the coldest region among the Mesosphere layers of atmosphere.