Which is the coldest region of the Earth’s atmosphere?

The Earth’s atmosphere is divided into several layers, each with distinct temperature characteristics. These layers are the troposphere, stratosphere, mesosphere, thermosphere, and exosphere. Among these, the mesopause is the coldest region.

The mesopause is located at the upper boundary of the mesosphere, approximately 80–85 km above the Earth’s surface. At this altitude, temperatures can drop to around −90°C (−130°F) or even lower during certain conditions. The extreme cold is due to the low absorption of solar radiation and the thin density of air molecules at this height, which cannot retain heat efficiently.

In contrast, the thermosphere, located above the mesosphere, experiences very high temperatures because it absorbs high-energy solar radiation, but despite the high temperature, the air is so thin that it would not feel hot. The stratopause marks the upper boundary of the stratosphere, where temperatures are moderately warm due to the ozone layer absorbing ultraviolet radiation. The exosphere is the outermost layer, where gases are extremely sparse and temperatures can vary widely depending on solar activity, but it is not the coldest region.

Understanding atmospheric layers and their temperature characteristics is important in physics, meteorology, and space science. The mesopause is critical in studies of atmospheric circulation, noctilucent clouds, and upper-atmosphere phenomena.

In summary, the mesopause is the coldest region of the Earth’s atmosphere due to its high altitude, minimal absorption of solar radiation, and very thin air density. This layer plays an important role in understanding temperature gradients and the dynamics of the upper atmosphere.