What Are the Dog Days of Summer?
UPDATED July 17, 2015
By WeatherBug Chief Meteorologist, Mark Hoekzema
Many people use the term "Dog Days" when referring to the hot days of late summer that seem to drag on endlessly in some years. The term brings up images of dogs lying on the front porch on hot summer days, not moving for fear of overheating. Many people think the term "Dog Days of Summer" comes from the idea that it is the period of extended heat in the mid- or late summer that sends dogs running for the cool shade of a porch or tree.
A dog does play a role in the history of the term, but it actually is a celestial dog. Back in early civilizations, people looked at the stars and pictured that the brightest ones formed images of animals. Many saw bears, bulls, lions and yes, dogs. These are called constellations and the constellation Canis Major is one that depicts a dog. The brightest star in this constellation is Sirius or the "Dog Star."
In ancient Rome, it was actually believed that since Sirius was so bright it actually heated the earth. Sirius is visible in the winter in the southern sky, but between early July and mid-August it actually rises during daylight with the sun. Ancient Romans believed that this star actually added heat to the heat of the sun, thus the reason the days were the hottest during this period. Thus, the reason these later days of summer are called the "Dog Days" of summer!
We now know that the hottest days of the year occur during these "Dog Days" because the earth is tilted towards the sun. Because of the tilt the earth stores up heat and becomes hotter until mid-August when the cooling begins. Despite the reasoning for this hot time of year, this period of time still sends dogs running to the shade of cool porch.
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Story Image: P`Nut enjoys a few tennis balls. Submitted by WeatherBug user Carmel McGuire of Germantown, Md.
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