Temperature
There are many factors that affect water temperature. For instance the color of the water, dark murky water will absorb more heat making it warmer while clear water will generally be cooler. How deep the water is also affects the temperature. Other variables are the amount of shade water receives, where the water is located worldwide, the time of the year, the temperature of the water supplying the waterway, and the amount of water. Most aquatic organisms are cold-blooded and therefore usually become more active in warmer water. Fish and other aquatic organism usually have their own optimum, or best, temperature. If the temperature varies too much from their optimum, they may have trouble surviving.
1. Open the silver, metal arm of the thermometer.
2. Measure the air temperature in the shade. Hold for approximately 2 minutes. Record temperature*.
3. Hold thermometer in water for about 30 seconds. Be careful not to get black or gray part wet. Record temperature*.
* All temperatures should be rounded to the nearest degree.
What Do the Results Mean?
You will find that although most narrow bodies of water are shallow enough to allow penetration of sunlight the water temperature is quite low. One factor which contributes to this is the heavy growth of vegetation shading the stream, preventing the sun from warming the water. The most significant cooling factor is the rapid rate of evaporation. Think about how you would stir a hot liquid to increase surface area from which evaporation can take place, resulting in faster cooling of the liquid.