Which ionospheric region most affects sky-wave propagation on the 6-metre band?

The 6-metre band is generally considered a VHF band where normal F-layer skip is rare, usually only occurring during the absolute peaks of the 11-year solar cycle. However, the E region frequently enables long-distance communication on this band through a phenomenon known as Sporadic-E (Es) propagation. Sporadic-E involves highly ionized, temporary clouds forming in the E region of the ionosphere, particularly during the summer months. These clouds are dense enough to refract 6-metre signals back to Earth, allowing for exciting, unpredictable contacts over hundreds or thousands of kilometers. While the F1 and F2 regions are the primary drivers for high frequency (HF) sky-wave propagation (like 20 metres), the 6-metre band's most famous and reliable sky-wave mode relies entirely on the E region.