On 01/18/2011 04:30 AM, Keith wrote:

The sun spots are very low right now which effects the ionosphere.
Here is a short article on the concept:

http://hamchatforum.lefora.com/2009/11/13/hf-radio-propagation-and-sunspots/


Here's a shorter one:

In order for signals to refract (be bent back toward the Earth) the
ionosphere needs ions. These are produced when UV radiation interacts
with the atmosphere. UV radiation comes from Sunspots.