The mesosphere is the segment of the Earth's atmosphere residing between the stratosphere and the thermosphere. It is the least-studied and least-understood layer of the atmosphere.
The mesosphere resides between 31 and 53 miles above the Earth's surface. This places it too high for weather balloons but too low for satellites. Samples taken from the mesosphere indicate high levels of metals, such as iron. This is the result of meteors vaporizing in the mesosphere and leaving bits of debris behind. Near the Earth's poles, high altitude noctilucent clouds form in the mesosphere, complete with electrical activity. Noctilucent clouds comprise water ice and appear around twilight, when the sun is beneath the horizon.
During some thunderstorms, colorful electrical activity occurs in the mesosphere. Red sprites are flashes of red that occur directly above thunderstorms in conjunction with cloud-to-ground lightning. Cloud-to-ground lightning also produces red disk-shaped discharges in the mesosphere known as elves. Blue jets are flashes of blue that expand upwards from the electrical charged center of a thunderstorm.
The upper segment of the mesosphere is the coldest region of the atmosphere with temperatures at nearly -150 degrees Fahrenheit. Low temperatures in the mesosphere are the result of less solar warmth and more cooling from carbon dioxide.