The third layer of the atmosphere is the:

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

Answer: (C)

Understanding how Earth's atmosphere is organized from the ground up helps explain why this layer is the third. From the surface upward, the layers are the troposphere, the stratosphere, the mesosphere, and the thermosphere. The third layer, the mesosphere, sits between the stratosphere above and the thermosphere above it. In this region, the air is thinner and temperatures generally decrease with height, making it the coldest part of the atmosphere. It’s also where most meteors burn up as they enter Earth’s atmosphere. For contrast, the troposphere is the lowest layer where weather happens and temperatures fall with altitude, the stratosphere contains the ozone layer and warms with height, and the thermosphere has very high temperatures due to solar radiation but extremely thin air.