Sporadic E or E_s is an unusual form of radio propagation using characteristics of the Earth's ionosphere. Communication distances of 800–2200 km can occur using a single E_s cloud.

As its name suggests, sporadic E is an abnormal event, but can happen at almost any time; it does, however, display seasonal patterns. Sporadic E activity peaks predictably in the summertime in both hemispheres. In North America, the peak is most noticeable in mid-to-late June, trailing off through July and into August. A much smaller peak is seen around the winter solstice. Activity usually begins in mid-December in the southern hemisphere, with the days immediately 

ES Map v1.0 provides a LIVE visual representation of Sporadic Es reflection points in the ionospheric E-Layer for 10 and 11m bands.

The map shows the latest reported Es clouds over the past hour.