Reflections: The dog days of summer

The dog days of summer
by William L. Bulla
Weekly Contributing Writer

Why do we call the hot, sultry days of summer "dog days"? Webster defines "dog days" as..."the period between early July and early September when the hot sultry weather of summer usually occurs in the northern hemisphere." But where does the expression come from? Why do we call the hot, sultry days of summer "dog days?"
The phrase "dog days" or "the dog days of summer"(Latin: Caniculae, Caniculares dies) refers to the hottest, most sultry days of summer. In ancient times, people studied the stars and drew images by connecting the stars. Different cultures saw different pictures. We now call these star pictures constellations and the ones we know came from our European ancestors. They saw images of bears, (Ursa Major and Ursa Minor); twins, (Gemini); a bull, (Taurus); dogs, (Canis Major and Canis Minor), and others.
The brightest star in the night sky is located in that image of the "big dog, (Canis Major). It is named Sirius, the "dog star." Because it is so bright, and because in the summer it rises and sets with the sun, the ancient Romans believed that the earth received heat from it resulting in a stretch of hot and sultry weather. They named this period" dog days" after the dog star. In today's world, in our hemisphere, we call that period from early July to mid-August "the dog-days of summer" even though the dog star has no connection with our weather.
The summer solstice in the Northern Hemisphere, or top half of Earth, is around June 21. That's when the sun reaches its most northern point over our planet. The days around June 20 are the longest of the year, and the rays from the sun beat almost directly down on use and warm us up.
You might think that the longest days of the year would be the hottest. But they are not. The hottest weather, on average, comes about a month after the summer solstice. This is because the amount of heat from the sun continues to accumulate during the long hot days, and the short nights don't allow as much heat to leave. The days start to cool down only after the days grow short enough to allow more heat to leave Earth's surface than arrives.
It is not the heat, they say, but the humidity. Humidity is the amount of moisture in the air. When the air has so much moisture in it, our bodies don't do a good job of cooling us down because sweat doesn't evaporate as quickly from our skin. That is why we feel so hot on a humid day. In fact, the temperature we feel may be warmer than the actual air temperature. This is called the heat index. As an example, if the temperature is 100 degrees and the relative humidity is 50 percent, the heat index, or the temperature we actually feel, is 120. Hot, humid days can be dangerous for humans and animals, so stay out of the sun and drink lots of water when the humidity is high.

William L. Bulla is a freelance writer residing in Washington County.