What causes rain storms to disappear off the weather radar?

199 viewsOtherPlanetary Science

I’m avoiding having to walk in the rain and I’m watching Wunderground and the rain cloud traveling from north to south over me seems to disappear from the system right south of me as I’m waiting for it to stop raining.

It looks like the rain is just traveling right over me and then poof. What’s happening?

In: Planetary Science

5 Answers

Anonymous 0 Comments

Weather radar works, essentially, by sending out radio waves in all directions and seeing (1.) how long it takes them to reflect off of something (like raindrops) and bounce back and (2.) how much of the original radio wave actually is bounced back.

The problem with this is that the Earth is curved, so eventually your radio waves, which move in a straight line, will simply leave the planet and head off into space. To resolve this issue, you can set up a bunch of radar relays to cover the whole region, and sites like Wunderground can compile all the separate radar site images into one nationwide “radar image” – but if a particular relay is damaged, down for maintenance, or otherwise inoperable at the time, the weather system will seemingly disappear from the map if that’s the only radar that could track it.

So if you happen to live near the southern boundary of a particular radar relay, and the relay to the south of yours is offline, it would look as though the weather system disappears not long after passing you.

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