In this age of advanced technology, with so many scientific discoveries under our collective belt, it may seem that our understanding of nature is essentially complete, with only a few details to be worked out. Yet when we look closer, these "details" sometimes prove significant. Profound mysteries remain unexplained, even when it comes to ubiquitous phenomena that concern us on a daily basis, like the weather. The behavior of earth's atmosphere is not only difficult to predict, but exhibits properties that challenge our fundamental understanding of air and water.

For example, clouds are composed of negatively charged droplets of water, called aerosol droplets. If negative charges repel one another, how can those droplets coalesce to form clouds? Further, the density of water droplets exceeds the density of air, which means they should settle to the ground, yet they do not. What keeps clouds aloft?

Besides oxygen and nitrogen, the atmosphere contains other gases including carbon dioxide and argon. The densities of these latter two gases actually exceed those of oxygen and nitrogen. If denser gases settle beneath the lighter ones, then why are we not breathing pure argon?

While the concentrations of atmospheric gases such as carbon dioxide can vary, the nitrogen-to-oxygen ratio remains stubbornly constant at 3.727. Atmospheric scientists work assiduously to push the measurement precision from four to five significant digits in the hope of uncovering even trivial variants. This constancy seems to hold everywhere — in cities, on farms, atop mountains, in deserts, over oceans. Even in wintry Siberia, where photosynthesis is nil, still the nitrogen-oxygen ratio is the same as in the jungles of the Amazon. Why does the nitrogen to oxygen ratio remain so remarkably constant? Is there some kind of stoichiometric constraint?

Humid environments retard evaporation. How then does an evaporating water molecule know the level of humidity in the air above, and therefore whether or not to evaporate?

The atmosphere supposedly rests on the earth because of pressure. We think of gas molecules pressing upon one another like a pile of bricks, the lowest ones pushing on the earth's surface. However, the atmosphere is a gas. By definition, gas molecules rarely touch one another. Therefore, atmospheric molecules should press rather loosely if at all. If so, why don't the strong winds up there blow the atmosphere away?

Book cover for The Fourth Phase of Water: Beyond Solid, Liquid, Vapor

For answers to these and other questions about the nature of water, see my 2013 book...

The Fourth Phase of Water Preview Chapters (PDF)

Related Question

Are The Laws of Nature Fixed?