WeatherWhys As this edition of “Weather Whys” hits the streets, it might surprise you to learn that the intensity of the sun’s rays today is equal to the intensity of the sun’s rays on August 20th. In fact, out of all of the times of the year, the most “surprise sunburns” occur starting right around mid-April and continuing into the first part of May.
The reason for the surprise? It’s usually not very hot outside at that time of the year, certainly not like it can be in August! But the sun could care less about the temperature, because what causes sunburn is ultraviolet radiation, and the more intense the sun (the higher it is overhead), the more intense the UV radiation.
The sun, in the Northern Hemisphere, is highest in the sky on the summer solstice, right around June 21st, when it is directly overhead at the Tropic of Cancer, which is at 23.5 degrees north latitude, almost 1,400 miles south of Presque Isle. This is also when we see our longest daylight of the year.
So, all you have to do to compare ultraviolet intensities, is to take the amount of time before the solstice, which today is about two months, and then add that same amount of time to the other side of the calendar from the Solstice. So the sun’s height in the sky today, at its highest point in its daily arc (known as solar noon) is the same today as it would be about two months after the Solstice, and again, since today is about two months prior to the summer solstice, my earlier statement that today’s sun has the same intensity as the sun on August 20th can be seen to be true.
Now the most intense ultraviolet radiation time of the year is known as the “Solar Sixty”. These are the 60 days with the strongest rays. This period runs from May 21 to July 21.
So now you know, if you burn easily, not to pay attention to how cool it may still feel outside, but to the calendar itself!
Ted Shapiro holds the Broadcast Seal of Approval from both the American Meteorological Society and the National Weather Association. An Alexandria, Va. native, he has been chief meteorologist at WAGM-TV since 2006. Email him at tshapiro@wagmtv.com.
