With the dog days of summer coming, it's time to think about keeping cool. Here are a few things to investigate.
1. How did the dog days of summer get their name? Ask everyone you know. Look it up at the library.
2. Among the ways people try to beat the summer heat is by using a fan. How does this keep you cool? One experiment is to place a thermometer in front of an electric fan. Leave it for five minutes and take the temperature. Now turn off the fan and take the temperature again, waiting five minutes to make sure the thermometer has time to change. Is there a difference? Why or why not?
3. Going swimming is another way to get cool. Take your thermometer for a swim by dipping it in water. (Make sure it is a thermometer that will not be hurt by getting wet. If you are not sure, ask an adult.) Take the air temperature first. Then take the water temperature. Then remove the thermometer from the water and watch it as it dries. You can lengthen the time the thermometer takes to dry by using a rubberband to hold some cotton or facial tissue around the bulb of the thermometer. Get the cotton or tissue wet along with the thermometer. Watch the temperature as the bulb and paper or cotton dry. What happens? What happens if you use a fan to blow air across the wet thermometer bulb? Does this help you understand the results of investigation number 2?
4. Some people have air conditioning. See if you can find out how air conditioners work. Does it have anything to do with what you learned from investigation 2 or 3? Click here for one explanation.
5. Some people just sit in the shade. On a sunny day, try taking temperatures in the open sun (shade the bulb of the thermometer with your hand or put the thermometer into a paper towel or toilet paper tube covered with foil so that the thermometer reading is accurate) and in the shade. Is there a difference? Where is it warmer?
6. Some people just go into the basement. If you can, take the temperature in a basement. If you can't go to a basement, take the temperature of cold water from the water tap. Since water pipes are buried underground, the temperature of your cold water will be the same temperature as underground. How much cooler is it underground?
Did you really ask everyone you know and try the library to find out why the late summer is called dog days? If you did and still didn't find out you can click here.