Q: How much water is in the atmosphere?
A: Sitting nearly in the middle of the vast North American continent, Madison has what is known as a continental climate. Continental climates are characterized by large annual extremes in temperature and humidity as well as very distinct seasons.
The continental nature of Madison’s climate is what makes a year’s worth of weather in Madison usually a lot more varied than a year’s worth in Seattle, for instance. There is an astounding 144 degrees difference between the all-time highest (107 on July 13, 1936) and all-time lowest (-37 on Jan. 31, 1951) temperature in Madison.
In addition, the amount of water vapor in the air can range from the barely detectable level in the midst of a deep winter cold spell to as much as 3.5 percent of every breath you take during a severe July heatwave. No matter what the season, the vast majority of the invisible water vapor in the atmosphere is contained in the lowest mile or two from its source at the surface.
At any one instant, the Earth’s atmosphere contains 37.5 million-billion gallons of water vapor – enough to cover the entire surface of the planet with 1 inch of rain if condensed. This amount is recycled, through evaporation powered by the Sun, 40 times each year in what is known as the hydrologic cycle.
In each of these 40 cycles, enough energy is expended to power the U.S. — the largest consumer of energy in the world — for 3,441 years! A truly astounding amount of energy.