Dog Days of Summer

The phrase “dog days” refers to the sultry days of summer, usually July and August. But where did the term dog days come from?

DogDaysThe Romans associated hot weather with the star Sirius because it is the brightest star in the summer night sky. They referred to those days as dies caniculares, or dog days, because Sirius is in the constellation Canis Major (Large Dog).

The Dog Days originally were the days when Sirius rose just before or at the same time as sunrise (heliacal rising), which is no longer true, owing to precession of the equinoxes.

Dog Days were popularly believed to be an evil time when “the Sea boiled, the Wine turned sour, Dogs grew mad, and all other creatures became languid; causing burning fevers, hysterics, and phrensies.” The Romans sacrificed a brown dog at the beginning of the Dog Days to appease the rage of Sirius, believing that the star was the cause of the hot, sultry weather.

Today Dog Days merely refers to a kind of languid, relaxed period where it is too hot to do much more than lay around.

How A Body Overheats

During exertion the body produces heat. To lose excess heat, the body uses a combination of radiation (loss of heat), convection (cooler air movement), conduction (contact with cooler surfaces), and evaporation (sweating). If surroundings are hotter than the body, it must shed excess heat by evaporation of sweat alone.

Unfortunately, copious sweating places a heavy load on circulation, which is needed to bring blood to the skin for cooling. As the body progressively dehydrates through sweating, circulation is compromised and heat storage begins to exceed heat removal.

This further increases the strain on the circulatory system in a vicious cycle. The strain increases heart rate, sweat rate, and core and skin temperatures. Eventually the strain can cause heat stroke if the body is not cooled by some other means than sweat.

Solutions are to drink small glasses of water every 15 to 20 minutes, remove yourself from the sun for at least 5 minutes while drinking water, avoid caffeine which causes your body to lose water, and avoid working outside at the hottest times of the day. The more you do to bring your body temperature down, the more you can reestablish equilibrium between heat storage and heat removal.

5 Ways to Stay Cool Without Air Conditioning:

  1. When it’s cooler outside than inside, open your windows instead of using air conditioning. Use a window fan, blowing toward the outside, to pull cool air in through other windows and to push hot air out. When it’s hotter outside than inside, close your windows and draw window coverings against direct sunlight.
  2. On hot days, delay heat-producing tasks, such as dishwashing, baking or doing laundry, until the cooler evening or early morning hours.
  3. Caulk around window and door frames, use weather stripping on exterior doors, and have a professional seal gaps where air can travel between the attic and your living space.
  4. Use energy-efficient lighting in your home. CFL and LED light bulbs operate cooler and cost less to use because most of their energy produces light instead of heat. Incandescent light bulbs, on the other hand, lose 90% of their energy as heat.  
  5. Leafy shade trees planted on the east and west sides of your home can improve comfort and decrease cooling needs by blocking heat and sunlight. You’ll still have the benefit of heat from the sun in the winter, after the leaves fall. Check with your local garden centre for recommendations.

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