In South Africa I have seen a lot of people covering their satellite dish LNB (Low Noise Block - simple english receiver/filter) with what it seems to be a 2 litre plastic bottle cut in half…not sure if it is a coke bottle. There are several funny pictures of umbrellas and even plastic bags circulating on the internet. BUT WHY? Typical answer will be “Not loss signal during bad weather or when it RAINS”.

PLEASE STOP IT…

I am from a broadcasting engineering background and part of my job is to provide technical training for their technicians. Often times I ask why do people do it…is it a lack of information, ignorance or not knowing the basics?
You basically obstructing the signal…well if you say its for snow falling on the LNB well maybe it might assist a little…but for rain…rain…really?

Some of the funny comments posted on FAQ forums:

This morning at the butchery we use out in Krugersdorp, I noticed that they had a plastic sleeve wrapped around their LNB, and the dish itself under a roof overhang. Not the first time I've seen something like this. I couldn't help but smile to myself, surely if that were to actually assist with rain outage in any significant way it would be widely known? But whenever I've read about the subject of rain distortion / scattering of signals the reference is to atmospheric conditions and not surface ones. So in the hope of putting this myth to bed (or a chance of learning something new) - can anyone offer info or a reference source in respect of whether any practical outage protection is at all offered by preventing the dish surface and LNB's face from suffering direct rain interaction? And what of the plastic "barrier" itself, can it interfere at all? Plus it does also get wet...Of course the butchery's dish is... 60cm

Here is another post:

The ONLY dubious claim any of these measures has is prevention of water ingress into the connections and protection of the plastic and of the barrier over the front of the Horn feed on the LNB against UV damage. There is some evidence that crows and other birds have the habit of pecking away at the plastic barrier ultimately breaking it and allowing water to enter the LNB…that is about it.

I actually like the answer this person is giving:

Yes, an empty coke bottle prevents everything from hangovers and arthritis to thunderstorms building up between your dish and the satellite. Or - a more honest answer - no. However, it might keep a bit of snow off the LNB cap.

Lets look at the basic…I will rather not be technical and use common sense answer.

Satellites are placed above the surface of the earth in orbit...using common sense that is way above the clouds.

Image credit

So when it rains the clouds are between your dish at home and the transmitting satellite in orbit. If it is not raining very hard some signal can be received but during heavy rain (thick dark clouds) the signal depreciates so much that your receiver can not show any pictures.