why dose signals of radio & TV in the night becomes clear?

Answer 1

Its called the skywave effect.

Skywave is the propagation of radio waves bent (refracted) back to the Earth's surface by the ionosphere. As a result of skywave propagation, a night-time broadcast signal from a distant AM broadcasting or shortwave radio station (or rarely, a TV station) can sometimes be heard as clearly as local stations. Most long-distance HF radio communication (between 3 and 30 MHz) is a result of skywave propagation. For decades Amateur radio operators, limited to lower transmit power than commercial radio, have taken advantage of skywave for distance or DX communication.

Answer 2

Because the signals are not competing with the Sun. The Sun broadcasts all kinds of radio noise on all kinds of frequencies. When it's blocked by the Earth at night, radio programs have less intereference to overcome. That's why some stations have to reduce power at sunset. Otherwise their signals would overlap other stations' on the same frequency.

Answer 3

No traffic in the night so the signals travel very soon

More over they r putting nice programs in the night

Answer 4

You must live near a place that does arc welding. During the day their operation generates a lot of static noise. At night they go home and the interference clears up.

Answer 5

Nights are more humid then days....
Humidity helps signals to travel to a longer distance without any distubance......
that's y in winters the smell and sound travel longer distances...

Answer 6

in day time the signals are incorporated with those from sun also(sun is radio emitter) and those from energy reflections from earth(this reflected energy is the one which is absorbed from sun light).
in the nite both of the above reasons are absent.

Answer 7

i don't know