The Sun has an approximately 11 year cycle in which the sunspot activity oscillates between relatively low and high levels. Among other things (such as long term weather patterns), the solar activity influences reception of short-wave transmissions over long distances. As of late 2007, we are going through a "sunspot minimum" which does not provide very good conditions for short-wave radio communications.
The image above from The Solar Physics Group at NASA's Marshall Space Flight Center shows the recent solar activity, the vertical axis indicating the position (latitude) of individual solar flares on the solar circle. (Click on the image to see a more detailed version.) Notice how flares move to central (equatorial) latitudes near solar actitivity minimum. A new solar cycle, on the other hand, is signalled by the first appearence of a solar flare at a higher latitude.
The "good news" for shortwave enthusiasts from the Solar and Heliospheric Observatory (SOHO) of the European Space Agency is that the small new solar flare which appeared today (December 12, 2007) on the upper left corner of the Sun in the image below may be the signal for the new solar cycle!
The Solar Influences Data Analysis Center - SIDC of the Royal Observatory of Belgium reports:
Conditions for shortwave radio communications are expected to improve in the coming years, reaching a new optimum in a few years. tracermcy2