Mesosphere

This characteristic is used to define limits: it begins at the top of the stratosphere (sometimes called the stratopause), and ends at the mesopause, which is the coldest part of Earth's atmosphere, with temperatures below −143 °C (−225 °F; 130 K).

[2][3][4][5] The stratosphere and mesosphere are sometimes collectively referred to as the "middle atmosphere",[6] which spans altitudes approximately between 12 and 80 km (7.5 and 49.7 mi) above Earth's surface.

On Earth, the mesopause nearly co-incides with the turbopause, below which different chemical species are well-mixed due to turbulent eddies.

The upper mesosphere is also the region of the ionosphere known as the D layer, which is only present during the day when some ionization occurs with nitric oxide being ionized by Lyman series-alpha hydrogen radiation.

Astronomers have begun utilizing this sodium band to create "guide stars" as part of the adaptive optical correction process used to produce ultra-sharp ground-based observations.

Often referred to as 'dunes' due to their resemblance to sandy ripples on a beach, the green undulating lights extend toward the equator.

[20][21] The presence of red sprites and blue jets (electrical discharges or lightning within the lower mesosphere), noctilucent clouds, and density shears within this poorly understood layer are of current scientific interest.

On February 1, 2003, Space Shuttle Columbia broke up on reentry at about 62 km (39 mi) altitude, in the lower mesosphere, killing all seven crew members.

Earth's atmosphere as it appears from space, as bands of different colours at the horizon. From the bottom, afterglow illuminates the troposphere in orange with silhouettes of clouds, and the stratosphere in white and blue. Next the mesosphere (pink area) extends to just below the edge of space at one hundred kilometers and the pink line of airglow of the lower thermosphere (dark), which hosts green and red aurorae over several hundred kilometers.
Diagram showing the five primary layers of the Earth's atmosphere: exosphere , thermosphere , mesosphere, stratosphere , and troposphere . From Earths surface to the top of the stratosphere (50 km) is just under 1% of Earth's radius.
Afterglow of the troposphere (orange), the stratosphere (blue) and the mesosphere (dark) at which atmospheric entry begins, leaving smoke trails, such as in this case of a spacecraft reentry.
An astronaut onboard the International Space Station observes lightning at the horizon extending into the mesosphere as red sprite just below the line of airglow .
Noctilucent clouds (not to be mistaken with the slightly higher up airglow ), at the upper edge of the mesosphere.