Editing Sporadic E propagation (section)

==Overview==
As its name suggests, sporadic&nbsp;E is an unpredictable event that can happen at almost any time; it does, however, display strong seasonal and diurnal patterns. Sporadic&nbsp;E activity peaks predictably near the solstices in both hemispheres. In the [[mid-latitude]] of the Northern Hemisphere, activity usually begins in mid-May, with the peak most noticeably beginning in early June. It begins trailing off after mid-July and becomes much less reliable by early August. A much smaller sporadic-E peak occurs during the winter solstice. For the mid-latitudes of the Southern Hemisphere, the timeframes are inversed; the highest activity occurring during their summer solstice.<ref name="notes">{{cite web |title=Using Sporadic E, Es Propagation for Ham Radio » Electronics Notes |url=https://www.electronics-notes.com/articles/ham_radio/amateur-propagation/sporadic-e-es.php |website=www.electronics-notes.com |access-date=30 October 2023}}</ref>

Communication distances of 800–2,200&nbsp;km (500–1,400&nbsp;miles) can occur using a single E{{sub|s}} cloud. This variability in distance depends on a number of factors, including cloud height and density. The [[Maximum usable frequency|maximum usable frequency (MUF)]] also varies widely, but most commonly falls in the 25–150&nbsp;[[Megahertz|MHz]] range, which includes the band&nbsp;II [[FM broadcast band]] (87.5–108&nbsp;MHz), band&nbsp;I [[VHF]] [[television]] (American TV channels&nbsp;A2–A6, Russian channels&nbsp;R1–R5, and European channels&nbsp;E2–E4, which are no longer used in Western Europe), [[CB radio]] (27&nbsp;MHz), and the [[amateur radio]] [[2-meter band|2&nbsp;meter]], [[4-metre band|4&nbsp;m]], [[6-meter band|6&nbsp;m]], and [[10-meter band|10&nbsp;m]] bands. On very rare occasions, a MUF of 225&nbsp;MHz can be attained.<ref name="notes" />

No conclusive theory has yet been formulated as to the origin of sporadic&nbsp;E. Attempts to connect the incidence of sporadic&nbsp;E with the eleven-year [[Sunspot cycle]] have provided tentative correlations. There seems to be a positive correlation between sunspot maximum and E{{sub|s}} activity in Europe. Conversely, there seems to be a negative correlation between maximum sunspot activity and E{{sub|s}} activity in [[Australasia]]. Harrison <ref>{{cite web |author=Harrison, Roger |title=Sporadic E - Stardust Propagation |publisher=Amateur Radio Magazine Volume 91 Number 1 2023|url=https://www.wia.org.au/members/armag/2023/january/}}</ref> implies that there is a correlation between the formation of sporadic&nbsp;E and iron/magnesium micrometeoroid ablation in the ablation zone, 100 to 140&nbsp;km (60 to 90 miles) above the earth surface. Maruyama discusses this possibility further.<ref>{{cite journal |author=Maruyama, Takashi |title=Meteor-induced transient sporadic E as inferred from rapid-run ionosonde observations at midlatitudes |year=2008 |journal=Journal of Geophysical Research: Space Physics|volume=113 |issue=A9 |doi=10.1029/2008JA013362 |bibcode=2008JGRA..113.9308M |doi-access=free }}</ref>