Idris Latif – Reuters
Enthusiasts watch a total solar eclipse near Mitchell, Oregon, on August 21, 2017.
Changes in temperature, wind speed, and humidity occur when the moon crosses in front of the sun during a solar eclipse and casts its shadow on the Earth’s surface.
The more sunlight is blocked, the more dramatic the climate changes. The effect is similar to how shaded areas are cooler on a hot day than anywhere exposed to direct sunlight.
Saturday’s annular eclipse will block up to 90% of the sun in a narrow path from Oregon to Texas. Annular eclipse It allows a slightly larger amount of solar radiation – sunlight and energy – to reach the Earth’s surface than a total eclipse, which blocks the Sun completely.
But a decrease in solar radiation, no matter how brief, can affect temperatures and other weather.
However, not all eclipse weather changes are created equal. The exact drop in temperature can vary greatly based on other factors such as the time of year and cloud cover.
An annular eclipse in October will have a less dramatic effect on temperatures than a total eclipse in August, not only because of the amount of sun blocked by the moon, but also because of the lower angle at which the sun strikes the Earth in the fall compared to the summer. .
A higher sun angle produces more intense brightness and higher temperatures, and the angle begins to decrease in the fall.
2017 Total solar eclipse It happened during a summer afternoon in August, so temperatures were already high, making it more likely to crater in some locations along the overall path. Temperatures dropped by 11 degrees in just one hour in Douglas, Wyoming, and there was a widespread drop in temperatures of 4 to 8 degrees across the South.
Jonathan Ernst – Reuters
People watch a solar eclipse approaching totality from Great Smoky Mountains National Park, Tennessee, on August 21, 2017.
The drop in temperatures during the solar eclipse on Saturday is not expected to be sharp, but it is possible that it will drop by a few degrees in… The ring road.
Areas that experience only a partial solar eclipse could see a slower rise in temperatures from late morning to early afternoon, Juan Hernandez, a meteorologist with the National Weather Service in Fort Worth, Texas, told CNN.
A slow rise in temperatures may limit how high temperatures can rise in the afternoon hours and leave Saturday a little cooler than if there was no eclipse. This may happen in Dallas and Phoenix, where the moon will block 80% of the sun.
Eclipses affect more than just temperature. Reduced solar radiation and lower temperatures can also affect wind, humidity and cloud cover.
The rapid cooling down during an eclipse briefly reduces the amount of heat stored in the atmosphere. Heat forces the air to rise and makes the atmosphere unstable. The atmosphere then creates clouds, storms, and winds to release thermal energy in an attempt to rebalance itself.
So when an eclipse cools the air, the atmosphere calms down and wind speeds decrease because the atmosphere isn’t working as hard to balance itself. Scientists made a number of weather measurements in Wyoming and New York during the 2017 total solar eclipse And he found Wind speeds decreased by 6 mph as a result of the eclipse.
How humid you feel is closely related to temperature. Humidity rises when the air temperature and dew point, which measures the amount of moisture in the air, are close to the same temperature. So when air temperatures drop briefly during an eclipse, it approaches the dew point and makes the air a little more humid.
A significant drop in temperature can also change cloud cover.
Clouds disappeared over parts of South Carolina during the 2017 total solar eclipse because they lost their fuel — the heat that forces air to rise and form clouds. It’s also possible that some clouds will dissipate during Saturday’s solar eclipse, even as temperatures drop less severely.
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