In the troposphere, the lowest level of the earth' s atmosphere, the temperature decreases as one progresses straight upward  At the top, the air temperature ranges from -50 degrees Celsius over the poles to -85 degrees Celsius over the equator  At that point the stratosphere begins, and the temperature stops decreasing and instead increases as one progresses straight upward through the stratosphere  The stratosphere is warmed by ozone
When an ozone particle absorbs a dose of ultraviolet sunlight, heat is generated
The temperature at any point at the top of the stratosphere is at least as great as the temperature at the top of the troposphere directly beneath that point.