Another Humidity Question

[imprimis]

Okay, I have a still-air hova-bator in which I installed a pc fan in it which is the smartest thing I have ever did. I can't believe in how much better it keeps the temperature constant. I have it in the garage, (I know it's not supposed to be out of the house) but even in extreme temp swings, from 50 to 80 in one day, the fan has kept it constantly at 99.5.

To the question, it's really humid here in Michigan, down right muggy. It's so humid my garage floor is sweating. Being that it's around 80% humidity in the garage, why is it only 34% in the bator? Is it because of the added fan drying it up in there. I know it should have water added to the bottom but when I did, the humidity shot up to 70%. I thought the bator would take on the same reading as it's environment. Any suggestions?

 

[VanSintjan]

We've had really high humidity here in Belgium for a while but my incubator only vent up araound 5% in an average. I have a small pan with water in it and humidity stays around 50% +/- 5%.
I think it's the fan.
When I hatched the last ones I had the entire bottom of the bator filled with water plus wet sponges and I had between 70 and 75% humidity during the hatch even though we had close to 80% humidity in the room.

 

[muffi]

Relative humidity, which is what we really mean when talking about humidity with regard to incubators, compares the amount of water in the air to the maximum that it could hold AT A GIVEN TEMPERATURE. Therefore, when it is 80% humidity outside at 80 degrees, if you heat that outside air to 99.5 degrees, the relative humidity goes down, just as you observed. And for those engineering freaks like me, here's a link to a chart that allows you to calculate this change: http://www.sp.uconn.edu/~mdarre/NE-127/NewFiles/psychrometric_inset.html . All you do is find the current temp along the bottom, go straight up to the relative humidity curve, then go straight across until you intersect the vertical line for the new temp (as in Example 2 on the website). Have fun!