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Name: Dave
Status: other
Grade: other
Location: WI
Country: USA
Date: Summer 2011

I train and use trail and tree hounds for hunting. I recently had a situation where the temperature was 68 degrees, humidity was 54% and dew point was 62 degrees. My dogs were not able to perform as well as other times when humidity was higher and temperatures were higher. They seemed to over heat quickly this time. How does the dew point affect how dogs breath under the conditions stated above?

You have to keep in mind what the terms "relative humidity" and "dew point" mean. They are related but they do not measure the same thing. Relative humidity is the amount of water VAPOR the air will be compatible with before condensing into liquid form. The dew point is how many degrees the temperature must be reduced from the ambient value to the temperature where the relative humidity is 100%. The difference between the dew point and the depression of the dew point increases as the temperature increases. Without going into the quantitative details (You can find the conversions in most any Chemical/Physics handbook.) Hot and dry increases the rate of evaporation more (Hence cools the dogs.) than cooler and moist which retards the evaporation of water from the dog's skin.

Vince Calder

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