Early Saturday Morning...

[electra225]

I was going to guess the Heaviside Layer. I have an old radio book that talks about the Heaviside Layer. I listen to a radio station that increases it's power at daylight. I can get the station before daylight in the summer. Weakly, to be sure, but I can get it. In the winter, I can't even get a carrier until they increase the power at daylight. I can also not get WBAP in Dallas/Fort Worth at all here in the summer. I can in the winter if I use the right antenna. I can't get it on my Hallicrafters SX-110, but I can get it on the Stromberg-Carlson 1121. The difference? The antenna.

[19&41]

You're right Greg, I had always seen it referenced in the Army by it's altitude. I didn't know it figured prominently in the musical "Cats".

[electra225]

I'm not sure I understand all I know about the Heaviside Layer. My understanding is that it deals with the curvature and rotation of the earth in relation to the position of the sun. This is why DX-ing either works better or not, depending on the season.

[TC Chris]

The sunspot disruption of RF propagation continues, according to SpaceWeather:

"NOAA forecasters have boosted the chance of M-class solar flares today to 25%. This is in response to the continued growth of AR3141. The big sunspot now has a 'beta-gamma' magnetic field that harbors energy for moderately-strong explosions. Any flares will be geoeffective as the sunspot is turning toward Earth. Solar flare alerts: SMS Text"

Then the site went on to discuss the lunar eclipse. I got up at 5:10 a.m., not my usual pattern, and put on a bathrobe to wander out in the front yard and look NW for the eclipse. What did I see? Clouds. @#*&^%!!! Overhead I could see breaks in the clouds but not at a NW angle. Back to bed, warm & cozy again.

Chris Campbell

[TC Chris]

I was just checking the SpaceWeather site and found this explanation for solar effects on radio propagation:

"Space weather impacts radio communication in a number of ways. At frequencies in the 1 to 30 mega Hertz range (known as “High Frequency” or HF radio), the changes in ionospheric density and structure modify the transmission path and even block transmission of HF radio signals completely. These frequencies are used by amateur (ham) radio operators and many industries such as commercial airlines. They are also used by a number of government agencies such as the Federal Emergency Management Agency and the Department of Defense.

There are several types of space weather that can impact HF radio communication. In a typical sequence of space weather storms, the first impacts are felt during the solar flare itself. The solar x-rays from the sun penetrate to the bottom of the ionosphere (to around 80 km). There the x-ray photons ionize the atmosphere and create an enhancement of the D layer of the ionosphere. This enhanced D-layer acts both as a reflector of radio waves at some frequencies and an absorber of waves at other frequencies. The Radio Blackout associated with solar flares occurs on the dayside region of Earth and is most intense when the sun is directly overhead.

Another type of space weather, the Radiation Storm caused by energetic solar protons, can also disrupt HF radio communication. The protons are guided by Earth’s magnetic field such that they collide with the upper atmosphere near the north and south poles. The fast-moving protons have an affect similar to the x-ray photons and create an enhanced D-Layer thus blocking HF radio communication at high latitudes. During auroral displays, the precipitating electrons can enhance other layers of the ionosphere and have similar disrupting and blocking effects on radio communication. This occurs mostly on the night side of the polar regions of Earth where the aurora is most intense and most frequent."

Chris Campbell