Here's how it works:

* Ozone Layer: The stratosphere contains a layer of ozone (O3) gas. This ozone layer is crucial because it absorbs most of the sun's harmful UV radiation.

* Absorption of UV: When UV radiation hits the ozone molecules, it causes them to break apart and then recombine, releasing heat in the process.

* Temperature Profile: This heat absorption is the reason why the stratosphere gets warmer with altitude, unlike the troposphere (the layer below), where temperature decreases with altitude.

While other forms of solar radiation reach the stratosphere, UV radiation is the primary source of warming.