<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD> <META http-equiv=Content-Type content="text/html; charset=iso-8859-1"> <META content="MSHTML 6.00.2900.2802" name=GENERATOR> <STYLE></STYLE> </HEAD> <BODY> <DIV><FONT face=Arial size=2><EM>Bob Davis wrote:</EM></FONT></DIV> <DIV><FONT face=Arial size=2><EM>Relative humidity is the amount of water vapor in the air, versus the amount it can hold, at a given temperature. If the temperature is, say, 70 degrees, and the air is holding all the moisture it possibly can, the RH is 100 percent. Since warm air holds more water than cold air, if the temperature then rises, the RH would go down, since the warmer air would be capable of holding more water.</EM></FONT></DIV> <DIV><FONT face=Arial size=2><EM></EM></FONT> </DIV> <DIV><FONT face=Arial size=2><EM>Ambient humidity is just the relative humidity at a particular location, like in the living room where the piano sits.</EM></FONT></DIV> <DIV><EM><FONT face=Arial size=2></FONT></EM> </DIV> <DIV><FONT face=Arial>Exactly, Bob.</FONT></DIV> <DIV><FONT face=Arial size=2></FONT> </DIV> <DIV><FONT face=Arial color=#808080 size=2><EM>Don Rose, B.Mus., A.M.U.S., A.MUS., R.P.T. wrote:</EM></FONT></DIV> <DIV><FONT face=Arial color=#808080 size=2><EM>Suppose you have 1 liter of air and it is at 20 degrees Celsius. Suppose<BR>the measured humidity inside the container is 30%.</EM></FONT></DIV> <DIV><FONT face=Arial size=2><EM></EM></FONT> </DIV> <DIV><FONT face=Arial>Absolute humidity or relative humidity?</FONT></DIV> <DIV><FONT face=Arial size=2><EM></EM></FONT> </DIV> <DIV><FONT face=Arial color=#808080 size=2><EM>If one increases the<BR>temperature without allowing any air to escape the humidity will remain at<BR>30%.</EM></FONT></DIV> <DIV><FONT face=Arial size=2><EM></EM></FONT> </DIV> <DIV><FONT face=Arial>The absolute humidity would remain constant, but the relative humidity would decrease in the scenario above.</FONT></DIV> <DIV><FONT face=Arial></FONT> </DIV> <DIV><FONT face=Arial size=2><EM><FONT color=#808080>If on the other hand one allows air to escape--then there are fewer<BR>molecules of air--and fewer molecules of water so the "relative" humidity<BR>will be lower.</FONT></EM></FONT></DIV> <DIV><FONT face=Arial size=2><EM><FONT color=#808080></FONT></EM></FONT> </DIV> <DIV><FONT face=Arial size=2><FONT color=#808080><FONT color=#000000 size=3>Impossible to predict without additional information. Are we still increasing the temperature? Are we allowing the environment in the one liter vessel to equilibrate with the surrounding atmosphere? Theoretically, if one opens the vessel, and if the humidity outside was 100%, then both absolute humidity and relative humidity could rise in the vessel.</FONT></FONT></FONT></DIV> <DIV><FONT face=Arial size=2><FONT color=#808080><FONT color=#000000 size=3></FONT></FONT></FONT> </DIV> <DIV><FONT face=Arial size=2><FONT color=#808080><FONT color=#000000 size=3>By itself, relative humidity has nothing to do with "letting air escape".</FONT></FONT></FONT></DIV> <DIV><FONT face=Arial size=2><FONT color=#808080><FONT color=#000000 size=3></FONT></FONT></FONT> </DIV> <DIV><FONT face=Arial size=2><FONT color=#808080><FONT color=#000000 size=3>Terry Farrell</FONT></DIV> <DIV><EM><BR></EM></DIV></FONT></FONT></BODY></HTML>