By Randy Jackson

I was in my early teens when I first heard the song “Both Sides Now,” a Joni Mitchell song first made into a hit by Judy Collins. Like my contemporaries back then, I was more into the burgeoning rock and roll scene, which didn’t include Judy Collins. But even though I first thought the song was more fitting for my parents’ generation, I was struck by its emotional power, which still resonates when I hear the song today.

It’s the first verse of the song, about the variability of clouds, that sets the stage for the subsequent verses on love and on life. As the song goes, clouds can be like ice cream castles in the air, yet they rain and snow on everyone. Clouds at times represent both the beauty of nature unfolding before us, and at other times they are the raw unleashed power of nature itself. It’s no wonder Joni wrote the line, “I really don’t know clouds at all.”

Clouds, whether they form ice cream castles or storms, are the visual manifestation of climate. Clouds (rain), or their absence (drought), have maintained and destroyed civilizations. Here in Huatulco, we are on part of the lands of the earliest mesoamerican civilization, the Zapotec, the people of the clouds. Although many of us are seasonal visitors here, avoiding the clouds, snow, and storms of winter, globally we continue to see more severe weather events, so it might be wise to know a little about clouds.

Four different cloud types – an interesting sample!

Cloud Type: Shelf Cloud
Photograph location: Yucatan, Mexico

A shelf or wall cloud has a dark bottom and a clearly defined structure low to the ground. Photographs of these clouds are among the most striking images of storm clouds. These cloud formations are very common (although typically not this clearly defined). They bring thunderstorms – if one is approaching, take cover.

Cloud Type: Anvil Cloud
Photograph location: Near the France/Italy border

An anvil cloud occurs when updrafts reach a point in the atmosphere where the cloud can no longer rise so it spreads out in all directions. This is also a thunderstorm cloud, with strong lightning wind and rain potential.

Cloud type: Overshooting Top
Photo Location: Greece

An overshooting top has such powerful updrafts that it bursts above the layer of an anvil cloud forming a dome much higher in the atmosphere. If this dome is sustained for 10 or more minutes, very severe weather is likely. If you see this formation, take shelter.

Cloud type: Roll Cloud
Photo location: Uruguay

A roll cloud is not a bad weather cloud. It occurs when there is a boundary like a cold front or certain breezes that cause a horizontal vortex, often over bodies of water. These unique clouds are fairly rare.

It’s no wonder Joni Mitchell’s line “I really don’t know clouds” has such universal appeal. Clouds are complicated. The International Cloud Atlas has two volumes with 224 pictures describing 10 main cloud families divided into 14 species. Do you know what the largest supercomputers in the world do (besides quantum mechanics)? Weather forecasting. And as we know, they don’t always get it right.

It turns out that clouds are a bit of a wild card in modeling climate change scenarios. Cloud formation modeling requires extremely fine-scale physics. The behavior of water droplets (what clouds are) in concert with temperature, humidity, winds, and numerous other weather variables, cannot be fully calibrated even with today’s supercomputers. However, advances in machine learning may have helped scientists take a step towards more accurate modeling of clouds. Author Chelsea Harvey, in “Clouds May Speed Up Global Warming” (Scientific American, July, 2021), outlines the results of recent machine learning algorithms on cloud formations and climate change. Unfortunately, new computer modeling rules out most of the moderate climate change scenarios. Although bad news for us all, at least knowing something more about clouds is helpful.

The scientific study of clouds is certainly over my head (pun intended, insert chuckle or groan). But there is one thing we all do know about clouds: they can be astoundingly beautiful. One recent morning at Santa Cruz bay, for example, a large bank of dark clouds dominated the horizon. The rising sun, just behind one corner of the cloud structure, was brilliantly illuminating the upper edge of the clouds while projecting geometric rays into the atmosphere. Down below, at the edge of the far horizon, rain clouds connected with the sea. And with the sea and sky the same slate gray color, Santa Cruz bay looked like a water ramp up to the clouds, meeting, as parallel lines seem to join at the farthest point of our vision. It was maybe one of a million beautiful cloud vistas on earth that day. I wonder how many other observers of such vistas, like me, started humming “I really don’t know clouds at all.”

*refer to the post in the magazine to see the photos of clouds with the descriptions