LiveMusic Posted June 27, 2002 Share Posted June 27, 2002 It's common to hear "I hate this heat. 92*, 80% humidity." Something like that. Is that possible? Isn't it more like 50% humidity? If it's 92*, 50%, it's muggy as hell. If it were 80% humidity, wouldn't the dewpoint be like 84*? Is that possible? If dewpoint is 72*, isn't that muggy as hell? What does all this mean? If it's 100% humidity, is it raining? Do you ever see 80% humidity with it NOT raining? > > > [ Live! ] < < < Link to comment Share on other sites More sharing options...
Tedster Posted June 27, 2002 Share Posted June 27, 2002 A good explanation is at: http://daphne.palomar.edu/jthorngren/measures.htm Relative Humidity: we can compare how much water vapor is present in the air to how much water vapor would be in the air if the air were saturated. For this we use relative humidity. Relative humidity is a ratio that compares the amount of water vapor in the air with the amount of water vapor that would be present in the air at saturation. One way it can be stated would be as the ratio of the actual mixing ratio to the saturation mixing ratio. Relative humidity is given as a percentage: the amount of water vapor is expressed as a percent of saturation. For example, if a parcel of air at sea level, at a temperature of 25 degrees C, would be completely saturated if there were 20 grams of water vapor in every kilogram of dry air. If this air actually contained 20 grams of water vapor per kilogram of dry air, we would say that the relative humidity is 100%. If the parcel of air (at sea level at 25 deg C) actually had 10 grams of water vapor per kilogram of dry air, what is its relative humidity? 10 grams divided by the 20 grams it would take to be saturated, or 50%. If a parcel of air (at sea level at 25 deg C) had 18 grams of water vapor per kilogram of dry air, what is its relative humidity? Answer 3M. 18 grams divided by the 20 grams it would take to be saturated, or 90%. For a relative humidity to be 100%, it would mean that the air is completely saturated with moisture...and basically, you couldn't evaporate any more water vapor into it. Dew point is the temperature to which air must be cooled for water vapor in the air to condense to water droplets, and hence is a measure of moisture in the air. Warm air can hold more moisture than cool air, so, by cooling air, we lower the air's ability to hold water vapor. The more moisture in the air, the higher the dew point temperature, or, the less you have to cool an air parcel for it to become saturated. Here's another page that gets a little more mathematical...just a tad... http://www.agsci.kvl.dk/~bek/relhum.htm "Cisco Kid, was a friend of mine" Link to comment Share on other sites More sharing options...
eh steve Posted June 27, 2002 Share Posted June 27, 2002 go read some songwriting books in the AC f00; didn't you just talk about the weather with your mama tonight? http://www.homestarrunner.com/sbemail36.html Link to comment Share on other sites More sharing options...
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