Primer

Dry-Bulb? Wet-Bulb? What's the Difference?

Dry-bulb and wet-bulb thermometers measure two different types of heat. Understanding them is crucial to understanding building science.

Although the acts of melting ice and boiling water are mundane occurrences, the underlying physics are not so simple. The illustration shows what happens to the temperature of water as heat is added (Btu per pound on the horizontal axis). The graph shows plateaus at 32ºF and 212ºF. Why does the temperature hold steady, even as heat is being added, right at water’s melting and boiling points?

Published June 29, 2012