Heat from Breath

In an earlier post, we looked at how much water is lost through breathing.  Today, we’ll consider the amount of body heat lost through breathing.  Of course, depending on surroundings, air movement, and  how one is dressed, a lot of (or a little) heat might be lost through the skin, but we’re just considering the part that goes out with your breath.

Buoyancy

I used to read to my kids from a popular children's book which featured a curious monkey who got into trouble by grabbing a large bunch of helium balloons from a balloon salesman.  According to the storyline, the monkey was carried out over the city hanging from the balloons.  Now, I'm sure the illustrator for the book was deeply interested in thermodynamics (isn't everyone?) but may have been in too much hurry to calculate the appropriate number of balloons.  Or maybe artistic aesthetics overruled thermodynamic accuracy.  In any case, today we'll go back and look at the situation in more depth.

The Cyclic Relation

The cyclic relation is a result from calculus that is often used in thermodynamics to generate relations between properties.  Today we’ll talk about the cyclic relation and demonstrate it from tabulated steam table properties.

Moisture and the Speed of Sound

Many of us first learned about the speed of sound as children when we were taught that counting the seconds between the flash of lightning and the sound of the thunder provided an estimate of the distance to the lightning strike (around 5 seconds per mile).  Later, perhaps, we learned that the speed of sound is calculated by sqrt(k*R*T) where k is the specific heat ratio, R is the gas constant for a particular gas, and T is the temperature.  Obviously, the speed of sound varies with the temperature, but it also varies with the makeup of the air (through k and R).  So, does humidity have a significant effect on the speed of sound?  We’ll explore that question today.

Moisture and Altitude

Psychrometric charts are very useful for determining properties of moist air, but it is important to remember that each chart is prepared for a given atmospheric pressure.  Of course, it is easy to find charts created for specific elevations, but it is sometimes hard to visualize the variations in properties with elevation.  In this post, we’ll look at the effect of elevation on the moisture content of air.

Visualizing Thunderstorm Heat

When water vapor in the atmosphere condenses into liquid water we first get clouds, then rainfall.  But water vapor only condenses when heat is taken away from it.  So I got to wondering how much heat movement is involved in a rainstorm.

A Cold Snap, Part 2

In the last post, we talked about the ground temperature during a cold snap.  Today, we’ll look at the same situation from two different viewpoints.