HELENA — Wildfire smoke has been bad this summer, obscuring views and making it difficult and unhealthy to breathe. While the smoke is not cool, it may be cooling.
The thick haze in the sky has taken the edge off the heat and may be keeping temperatures several degrees shy of record highs.
Thick wildfire smoke has been found to drop daytime temperatures between 2° and 7° F from what is possible if the sky was clear. Similar to a cloud, the smoke can reflect a portion of the solar energy that reaches earth back into space, keeping surface temperatures a few degrees cooler.
However, smoke at night does not keep overnight temperatures warmer like clouds do. Picture a clear day and then a cloud moves in front of the sun, you can feel the temperature cool down.
Volcanic eruptions have had similar cooling effects on the earth. In June of 1991, Mount Pinatubo erupted in the Philippines, ejecting vast amounts of ash and gas high into the atmosphere.
Data collected following the eruption showed that the mean world temperature decreased by about 1-3 degrees F over the next two years.
Another great example of cooler surface temperature because of the sun being blocked is a solar eclipse. In the great eclipse of 2017, areas under the total eclipse experienced a temperature drop up to 15-to-20°! Even parts of Montana not under the totality had temperatures drop a few degrees.
The smoke stinks, literally. But it also cools, which may just be a silver lining of all that gray haze outside.