Observations of Ionospheric Movements by the Use of a Large Aerial Array

The ionosphere does not behave like a smooth mirror for radio waves, but more like an irregular diffracting screen. When a radio wave is reflected from it, a random diffraction pattern is formed over the ground. Simple arguments can be used to show that this pattern will move over the ground with a velocity which is twice the horizontal velocity of the ionosphere. This phenomenon can be used for the detection of movements taking place in the ionosphere.