Solstice Sun Spikes on Doppler Radar
Today is the summer solstice when we have the highest sun angle of the entire year at 78.4° above the horizon at solar noon. Most people know this at the astronomical beginning of summer. One very good way to see how the sun angle changes by season is to look at the sun spikes which appear briefly on Doppler radar twice a day at sunrise and sunset. This happens when the sun is low enough to send radiation directly at the radar directly and it’s received by the Doppler radar and shows up as a “Sun spike”. It’s a false return due to the solar radiation hitting the Doppler receiver but it can show you the angle the sun is setting in the western sky.
If you use a compass you know a 0° bearing or heading is due north, 90° is due west, 180° is due south and 270° is due west. Well I decided to pull the radar data from last nights sunset as the Summer solstice approached. Then grabbed the radar data from the sunset December 20th, 2012 when we had the Winter Solstice. Check out the amazing difference:
Summer Solstice June 20, 2013 Sunset:
Winter Solstice December 20, 2012 Sunset:
The total change in sunset was 59° from a southwest sunset in the winter to almost a Northwest sunset in the summer.
All thanks to the tilt of the Earth on it’s axis.
