Let's talk about dew.
On crisp spring mornings, you often find your lawn coated in it, but by noon, much of it has evaporated. Similarly, upon driving to work, you crank up the warm defrost to quickly disrupt the condensation on your windshield. Or - my personal favorite - you feel a brisk, cool gust of wind as you watch a dark thunderstorm approach.
These events highlight a pervasive interaction between temperature and humidity that we deal with every day; yet surprisingly, many people (including scientists) take it for granted.
The principle underlying all of these phenomena is that warmer air can hold more vapor. But what does that mean exactly? It means that as the air warms, more and more water molecules can remain as vapor - a gas. Conversely, as the air cools, the air loses its capacity to hold on to vapor, and the vapor condenses into water on your windshield or glass of water. In fact, the amount of vapor the air can hold increases exponentially as the temperature of the air warms (see figure above).
But what does this have to do with physiology? Many amphibians, like the salamanders that I study, depend upon wet skin to breath. Because of this, they often live in moist environments (however there are some exceptions). And as we know, moisture occurs more readily with cooler temperatures. To leverage this principle, many salamanders become active at night - when it is cooler. By limiting their activity to dark, cool nights, their skin remains wet and permeable to oxygen and carbon dioxide. Even though salamanders (probably) can't 'dew' the computation, they certainly live within the mathematical rules.
But you can understand the math. And when you see dew forming on your glass of ice water, you can thank salamanders for helping you to see that the ice in your glass cooled the thin layer of air surrounding your cool drink resulting in vapor condensing onto your glass.
So a round of applause for salamanders.