Why do radio signals travel farther at night than in the daytime?

Answer 1

This has to do with the area above the earth known as the Ionoshere. During the daylight hours the sun and ultraviolet rays produce layers in the Ionosphere that are not favorable for the refraction of long wavelengths, AM radio signals are of long wavelengths. During the night conditions change and a layer forms in the Ionosphere called the F2 layer. This layer is around 200 miles in height and dense enough to bend long wavelength RF (radio frequency) back to earth. Although this can vary it generally bounces a signal back to earth 1500 miles from it origins. It can also bounce signal multiple times for more distance. During daylight hours these long wavelength signal are absorbed by lower layers or actually pass straight through the atmosphere and into space.

Answer 2

Actually, in general, radio waves do not travel farther at night than in the day. HF signals (AM, Ham Radio 160 meters through 10 meters) are propogated using the ionosphere. In the case of AM, during the day there is no effective use of the ionosphere by AM. At night, the ionosphere retracts to a much higher altitude (sort of), and gives the AM signal a greater distance on which to bounce.

For FM, every once in a great while, there can be favorable weather conditions (namely a temperature inversion) where warmer air is trapped above cooler air and can form a "duct" in which FM signals can be propogated. I've actually heard FM signals from NYC in Washington DC during the late afternoon before - not at night...

I hope this helps.

Answer 3

Am Radio At Night

Answer 4

The ionosphere a layer of the atmosphere that signals bounce off of is higher when out of direct sunlight. So signals travel farther at night.

Answer 5

2 Reasons. At night time the noise level is lower because it's cooler. And the Ionosphere cools and becomes a better reflector to radio signals that hit it at an angle.

Radio Signals actually bounce between the earth and the lower Ionosphere and at night the reflection is more efficient than during the day.

Answer 6

Hi, the answer is simple, because during the night there are less obstacles/interference from other devices/objects who stop/absorb radio signals, and plus, the sun rays affect also the radio waves longitude.

Cheers!

Answer 7

Solar radiation. Light waves interfere with radio waves. Solar flares are concentrated enough to cause disruptions in communications all over the world.

Answer 8

Fewer trucks on the road slowing it down... 3;^)>

Answer 9

It has to do with the temperature of the air. Can't say exactly, just something about it.