PROPAGATION
A moderately active season is at hand. About a month after the vernal (spring) equinox, geomagnetic activity is on a seasonal decline. Days in the Northern Hemisphere are longer, causing a thinning of the ionosphere and a lowering of the maximum usable frequencies (MUF). Additionally, the annual summer sporadic-E (Es) season begins around May 1st (sometimes during the last week of April). Activity is sparse during the first two weeks of May and then it picks up to approximately 60% of the days by the end of May. This is great news for 10-meter enthusiasts, so now is the time to send out your signals in hopes of catching some good propagation.
During the first days of May, oxygen ions in the E region of the ionosphere are being excited more and more by the increasing closeness of the Sun. This causes them to recombine with metallic ions that are also present in the E region. During this E season that starts in May and lasts through the summer, thin layers of these
