Sunset/Sunrise Spikes

Screen-shot captured from Ashley's
RadarScope iPhone app

This evening I was sitting on my front porch and felt like I should look at the radar for my area. To my surprise I noticed that there appeared to be this little spike of reflectivity. It started in the center of the radar area and headed up to the northwest. I knew what this was, of course, maybe some of our readers don't.  Now, I've never actually seen one in person... it's not too often one comes across a sunset spike on radar. So, I felt the need to share my screen-shot and maybe a little bit of information on these interesting little radar quirks we come across every once in a while.

There are two times a day that seeing a "sunspike" is possible. Once is at sunrise and the other is at sunset. This one is a sunset spike, a sunrise spike would be opposite the sunset spike - coming from the east instead of west. Think of it as the sun rises in the east, so it would be seen coming from the east and the sun sets in the west. Therefore, it make sense why this one is coming from a westerly direction. These little spikes are caused by the radar experiencing interference from the electromagnetic energy emitted by the sun. At a certain point during sunrise and sunset, the radar dish points directly at the sun and experiences this electromagnetic energy. It then emits this returned energy as the spike pictured to the left on the radar scan. The reason why these aren't seen so often is because it only lasts for a very brief amount of time. One must look at the radar at the perfect time to see it.