You may know the atmosphere can be divided into several layers. What is the furthest layer from here? Yes, it's the ionosphere. This layer plays an important role for radio communication. The molecules in the layer are ionized by the radiation from the Sun. These ionized molecules reflect radio waves from the ground. (of course, such waves with higher frequency can go through the layer though...) That is, we can send radio waves beyond the horizon. But this layer changes dynamically. So it is important to understand the phenomena and mechanism of it.
This picture is the experiment to observe winds in the ionosphere. The equipment of the rocket released the vapor of lithium. The flame color of lithium is red, so you can see a red clound in the image. It seems there are some other types of metal released. The scientists can figure out the dynamics of the ionosphere by analysing the transition of these clouds.
You can see the details about the experiment here.