Last night I took the dog out just as an excuse to admire the sky. To fully appreciate it I didn’t immediately reach for the camera, I waited for my mind to clear, bent my neck back and the sky’s beauty sent my consciousness adrift with the clouds. To a passerby, it looked as if I was waiting for my dog to sniff out the scene while I was being temporarily distracted. I realize there are practical priorities in life, but it’s not as if in our leisure we don’t indulge in frivolous activities. Why then did I feel a need to camouflage my intentions from my neighbors? Is it more evidence that we are mostly psychologically disconnected from our natural surroundings?
The gap is indeed psychological since our lives heavily depend on clouds in ways that are less obvious than others. The amount of water that evaporates from lakes and oceans and which condenses into clouds does not entirely fall back over bodies of water when the clouds’ droplets get large enough. Some of the rainfall naturally irrigates farmlands or helps build up reservoirs, some of which are used for hydroelectricity. Clouds also sporadically dampen sunlight and contribute to temperature gradients over both land and water. The ensuing pressure gradients lead to wind which mixes water and distributes nutrients. By spreading pollen, wind also assists the reproduction of many trees. The main ingredient of clouds along with carbon dioxide absorb infrared, making the earth suitable for life. It’s also why the dry, cloudless sky of deserts creates such a pronounced temperature gradient between night and day.
The clouds I saw, the ones portrayed above, are known as cumulus congestus. These sometimes grow into thunderclouds, which give clouds yet another important function. They fertilize the soil since lightning converts nitrogen into nitrate. Annually 1011 kg of nitrogen are naturally rendered useful, a figure that is coincidentally almost identical to the annual amount artificially produced for agriculture.
Clouds play an important role in the carbon cycle, converting some of the carbon dioxide released from volcanic activity, respiration, industry and transportation into carbonic acid. The acid then weathers rock, transforming silicates and releasing hydrogen carbonate. In oceans, organisms convert water-soluble hydrogen carbonate into insoluble carbonate which can be used for shells and exoskeletons.
Without impurities, clouds cannot form. They need dust from a variety of inanimate and living sources to act as condensation nuclei. But unfortunately they can also carry excessive impurities such as soot and sulfates that irritate lakes, trees, lungs and hearts. According to one hypothesis, particulate pollution increases the number of clouds formed. Since condensation does not affect the total amount of H2O present in the atmosphere, the presence of more clouds leads to a cooling effect from their ability to block sunlight. Having more clouds dampens but does not eliminate the degree of warming from greenhouse gas pollution. But in order to better predict increases in average global temperatures, clouds are currently included in climate models.
The one cloud-type that has not yet been included in models is the cumulus. It comes in several varieties at high, mid and low altitudes. Some of the mid-latitude cumulus evanesce; other types, as we mentioned, grow into cumulonimbus. And while we wait for climate scientists to optimize their models, the rest of us should continue to work at mitigating global pollution and at preparing our cities for the more intense or more common microstorms, hurricanes, and floods that will ensue for a while, regardless of our current actions.
But we should also contemplate clouds in idle moments. The positive experience provides us with one more reason why it’s worth the gargantuan effort to rescue ourselves not just from pollution but from the contemporary dissociation between sky and consciousness.