Equatorial plasma bubbles are an ionospheric phenomenon near the Earth's geomagnetic equator at night time. They affect radio waves by causing varying delays. They degrade the performance of GPS.[1]
Different times of the year and locations have different frequencies of occurrence. In Northern Australia, the most common times are February to April and August to October, when a plasma bubble is expected every night.[1] Plasma bubbles have dimensions around 100 km. Plasma bubbles form after dark when the sun stops ionising the ionosphere. The ions recombine, forming a lower-density layer. This layer can rise through the more ionized layers above via convection, which makes a plasma bubble. The bubbles are turbulent with irregular edges.
An equatorial plasma bubble could have affected the Battle of Shah-i-Kot by disabling communications from a communications satellite to a helicopter.[2]