Thread by @NWSAtlanta

With KJGX radar going down for refurbishment, radar is on our mind! So lets talk about something we get asked about a lot; what is this hole in the radar over the radar location? To answer, we need to learn a little bit about how radar works, and use some *gasp* math! (1/7) #gawx

Radar sends out electromagnetic waves in order to detect objects. At the most basic level, waves are generated by the dish, the waves travel out, hit objects and scatter, and then some amount returns back to the radar, which we can measure. (2/7)

You can think of this as the radar "shouting" and then "listening" for a return echo. So the radar has to do two things before listening - first shout (send out the waves), then switch modes to "listen" for the return. Our radar does this very fast - like, microseconds fast (3/7)

The time to "shout" and then start to "listen" is approximately 7 microseconds. But here is the thing - you can't "see" anything until you start listening. And when talking about electromagnetic waves, we are talking about things moving at the speed of light! (4/7)

So our shout has some distance it has traveled before we can hear anything back from it. Time for that math! The speed of light is approximately 670,616,629 mph. Speed = distance/time. So, we know speed, and we know time, so we can solve for just how far that wave travels! (5/7)

Plug it in, and you get that in 7 microseconds, that wave has already travelled 1.3 miles! So we can't see anything around the radar for 1.3 miles, because we aren't able to "listen" yet for that distance. So, how big is that hole in radar image...about 1.3 miles! (6/7)

So now you know why that hole is there! Use this knowledge however you like. Impress your relatives and friends with useless trivia knowledge, for instance! Otherwise, know that we have extensive knowledge in how our systems work, so we can better serve all of you! (7/7)