Which atmospheric layer lies above the stratosphere, has the coldest temperatures on Earth, and is where most meteors burn up?

• A. Stratosphere
• B. Troposphere
• C. Thermosphere
• D. Mesosphere

Answer: (D)

The key idea here is identifying the atmospheric layer where temperatures reach the lowest values and where incoming meteoroids encounter enough air to burn up. That layer is the mesosphere. It sits above the stratosphere and below the thermosphere. In this region, temperatures reach their minimum in the atmosphere, dipping to about -90°C near the top of the mesosphere (the mesopause). The air is thin, but there’s enough drag to heat and ablate meteoroids as they travel through it, which is why most meteor events occur in this layer. The stratosphere above it actually warms with altitude due to ozone absorption, so it isn’t the coldest and isn’t the main meteor-burn zone. The troposphere, the lowest layer, is where weather happens and temperatures generally decrease with altitude but not to the extreme cold of the mesosphere. The thermosphere is much higher and can be very hot due to intense solar radiation, so it’s not the coldest either.