You know it's springtime when...

[Rick Levy <Radiowaves@CompuServe.COM>]

>>Is summer a better time for FM DXing. I believe that winter is the
optimum time for AM DXing; could someone admonish/validate me.<<

Yes and yes.  Long winter nights are generally best for medium wave AM
DXing, where ionospheric propagation (skywave) is involved.  VHF FM is
another matter.  FM via the ionosphere is rare, and correlates highly with
sunspot numbers (11 year cycle).  Most FM DX propagation is
tropospheric, and affected by weather (temperature, pressure, moisture). 
>From personal experience, refraction and other conditions which bring FM
signals over the horizon generally improve in summer, often dramatically.
In particular, the temperature inversions which cause tropospheric
ducting are more likely to occur.  Though good FM DX "openings" can occur
at any season, the likelihood does seem to increase in summer.

Rick Levy  

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