Shimmering clouds and good wine

Last week I got an email with a photo showing a cloud that had erupted into a rainbow of color. There is a name for what happened: it’s called cloud iridescence or irisation. Some call it cloud rainbows.

What happens is individual ice crystals or water droplets in the cloud reflect, refract and disperse incoming sunlight. It’s like what happens when a rainbow develops. A rainbow is caused by reflection, refraction and dispersion of light in water droplets, causing a spectrum of light to appear in the sky. Also, the occurrence of cloud iridescence is a bit rare. If you saw this iridescent cloud and you took a photo, save it for the grandkids, it’s a keepsake.

Ask anyone in the business of agriculture what role weather and climate play in that business and you’ll likely be asked how much time you have. With the changes we are seeing in our climate, indeed worldwide climate, scientists are studying the effects on various aspects of human agriculture. Wheat dominates the agriculture of our region. Though, not far away are the vineyards of grape growers, with grapes that ultimately become the wine we drink.

Though grapes are grown worldwide, quality wine grapes occur within a very narrow climate range. Any shift in climate and long-term weather patterns may potentially affect the wine industry. Though climate change is not uniform, small changes will affect grape growers, and ultimately vintners and consumers. The range of grape growing climate zones is about 10° Celsius worldwide. For some grapes, like pinot noir, the range is even slimmer: 2° C, according to recent studies. The National Academy of Sciences advises that the general shift of warmer temperatures poleward will lead to a “huge shake-up in the geographic distribution of wine production in the next half century.”

A recent study states, “The shift in climate and the resulting changes to weather patterns and carbon dioxide levels may cause shifts to grape chemistry and the resulting quality of wine. This is already being determined worldwide,” write Michelle Renée Mozell and Liz Thach, of Sonoma State University Wine Business Institute, in a 2014 paper. “For wine production … the most miniscule modifications in proportions can produce the most major modifications in flavor.”

This study also states that “Changes in temperatures and humidity may increase the presence of insects and insect-borne diseases as their temperature limits move poleward. Many regions that are thought to be protected by their current climate from certain pests may find themselves now exposed to infestation and contagion. The Glassy-winged Sharpshooter has brought Pierce’s disease to California. With a lifting of temperatures, this disease may travel northward.”

Looking back at June, here are the results of our temperatures and precipitation. The mean precipitation for June is 1.04 inches. We were way off the mean with only 0.22 inches. The all-time record was 4.29 inches way back in 1934. We had a high temperature of 90.1˚F on June 20 (all-time high was 105˚F in 2015) and a low of 37.3˚F on June 10 (the all-time low was 36.0˚F in 2008). Our mean temperature for this June was 66.3˚F, while the all-time mean is 65.6˚F.

For the month of July, the Climate Prediction Center (CPC) is showing an equal chance of either “Above or Below” normal temperatures. Also, the CPC is showing the same equal chance of “Above or Below” normal precipitation.