Why can I only see digital OTA during the evening hours?

[120inna55]

I'm 80 miles SE of Dallas. I literally live in the woods. I have a Channel Master (#3649) antenna on top of a 50' tower. Installed in 1997. The coax comes into an unknown amp.

I can receive the following networks from DFW consistently during the evening only: (ABC-WFAA-8.1, 8.2 / Fox-KDFW-4.1, 4.2 / NBC-KXAS-5.1, 5.2 / WB-KDAF-33.1). The amp doesn't seem to make a difference.

In the evenings the signals hang around 62-80 (per the 942). In the daytime, I'm not likely to get a strong enough signal to see anything. I can never consistently pull-in CBS-KTVT-11.1 or UPN-KTXA-21.1.

Why are my signals better in the evening as opposed to the daytime? Is it somehow related to sunlight, more interfering OTA signals?

 

[mike5119]

There is one possible answer. During the day, the sunlight heat up more particles in the air, causing interfering with the signal. At night, the temperature is cooler so less particles bouncing around.

Just my 2 cents physics

Mike

 

[korsjs]

some stations turn up the signal at night.

 

[Jimbo]

120inna55,

korsjs,
some stations turn up the signal at night.

120inna55,
Many station have no digital feeds active until primetime, (not sure about your networks)

Most will run sub channels so there is a picture on the channels, but not all.
Most of the time ,where I live, there is no HD until evening.

Also, a lot of channels are running on low power still, until the FCC requires full power, that was a definite issue with my networks about a year ago, now I think my networks are up to full power,as they are easier to pick up.

Jimbo

 

[Jim5506]

The enhancement of long range night time TV reception over day time may be due to night time creation of temperature inversion layers in the atmosphere which channel the signal back toward the ground instead of allowing it to escape into outer space. During the day the heating of the earth causes convection currents to rise and break up these layers.

A similar result can be seen when the jet stream is mixed downward by daytime heating causing strong surface winds, and as the atmosphere cools in the evening, the mixing of the atmosphere subsides and the surface winds do also.

There is also a small solar wind effect. In the early morning, long distance TV signals can be enhanced westward, and in the late evening, they are enhanced eastward, but this is more for very long distance DXing (150 miles or more).

 

[Lorenzo]

Cool moist air is the best for propagation of tv signals. When I lived in Oregon 120 and 160 miles to my tv stations I used to always pray for rain (not that common in the high desert region of Central Oregon) as the crappy VHF reception from Eugene and Portland would be stellar in rainy weather. Hot dry summer days were the worst for reception. One bad thing though if your antenna is looking through trees the wet branches and leaves block tv signal more than dry branches and leaves.

Not sure what your amp situation is. If it's actually an amp and not a power supply for an antenna mounted preamplifier and removing it makes no difference leave it out. If it's a power supply for an antenna mounted preamplifier and it makes no difference when you unplug it- usually means that your preamp, power supply or wiring is bad. If you don't have an antenna mounted preamp one can make a big difference on especially the UHF reception.