Beginning roughly 80 km above Earth's surface, the atmospheric gas becomes
ionized by the Sun's light and transitions into a plasma, which can respond to
electric and magnetic fields. This electrically charged portion of Earth's
atmosphere, called the ionosphere, supports a variety of phenomena relevant to
space weather. In the ionospheric E region, which extends from approximately 90
km to 120 km above Earth's surface, the plasma can grow unstable as the result
of the interplay between gradients in its density and the presence of an
electric field. One component of this instability produces density blobs that
can disrupt radio signals passing through them (e.g., from an orbiting satellite
to a receiver on the ground) while a second component tends to modify the size
and shape of those density blobs. This presentation uses results from computer
simulations to show how the second component, though it does not directly create
the disruptive density blobs, is nonetheless crucial to their evolution and to
our ability to forecast their impact on communication.