what is a wet bulb

A wet bulb thermometer is used to measure relative humidity. It has to be used alongside a normal thermometer for comparison. And it's the kind of old fashioned thermometer that has the bulb of liquid at the bottom and the thin glass stem that the liquid is squeezed up as it heats and expands.

What you do is get some kind of wicking material a couple of inches long, and you put one end over the bulb at the bottom of the thermometer and the other end you hang in a glass of water so that the liquid is drawn up the wick to the thermometer bulb.

Because of evaporation, the wet bulb will always measure a slightly lower temperature than the dry bulb of the other thermometer. The drier the atmosphere, the quicker the evaporation rate, and the lower the wet bulb reading will be. The more humid the atmosphere, the slower the evaporation rate, and the higher the wet bulb reading will be. But it will always be lower than (or in 100% humidity equal to) the dry bulb reading.

So you note the dry bulb reading adn the wet bulb reading, and then you use RH (relative humidity) tables to find out what the humidity is.

It's very accurate, but more complicated and more time consuming than just getting a hygrometer that reads humidity as a percentage.

 

Interestingly, the preferred method to measure humidity in the big hatcheries is the wet bulb thermometer method, according to some university sources.

I already have the glass bulb type thermomters; I will add 6 inches of cotton shoe lace and tie over bold and set end in sup of water.

Also, do remember to check the egg itself for the correct amount of increase in the air cell.

 

Quote:I use a wet bulb. I also have a hygrometer in my incubator for comparison.

 

Bump up for us oldies and newbees wow i feel like i am learning every day here we never did this 20+ yrs ago Thanks