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martyb [soylentnews.org] writes:

UK Digital TV Platform Freeview blames weather for TV problems [bbc.com]:

Digital TV platform Freeview says that people around the UK are experiencing reception problems because of high-pressure weather conditions.

Freeview's free-to-air channels include those from the BBC, Channel 4, Channel 5 and ITV.

The website Downdetector has nearly 5,000 comments [downdetector.co.uk] from viewers reporting that they can't access channels at all, or that the picture is distorting.

[...] it isn't the high pressure itself which causes interference with TV signals. It's the presence of what is known as an atmospheric temperature inversion. A temperature inversion is when a layer of warm air overlays cooler air at the surface. Temperature usually decreases with height above the earth's surface, but when there is an area of high pressure, the air aloft sinks down towards the earth's surface and it warms up as it does so.

This creates a sharp thermal contrast in the atmosphere which TV and radio waves see as a physical boundary. There are many TV and radio waves travelling through the lower atmosphere and in such atmospheric conditions, these waves can be refracted or bounce off the inversion overhead and this enables them to travel much further than they would otherwise be able to.

In this way, the usually strong Freeview signals can experience significant interference with other, normally distant, signals from other sources.

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