2023-10-14 11:38:00
(CNN) — This Saturday’s Ring of Fire annular solar eclipse will alter weather conditions on Earth’s surface as it develops in the sky.
Changes in temperature, wind speed and humidity occur when the moon crosses in front of the sun during a solar eclipse and casts a shadow on the Earth’s surface.
The more sunlight is blocked, the more dramatic the climate changes. The effect is comparable to how shaded areas end up much cooler on a hot day than any location exposed to direct sunlight.
This Saturday’s annular eclipse will block up to 90% of the sun in a narrow path from Oregon to Texas. Annular eclipses allow slightly more solar radiation (sunlight and energy) to reach the Earth’s surface than a total eclipse, which completely blocks the sun.
But a reduction in solar radiation, however brief, can affect temperatures and other weather conditions.
However, not all eclipse weather changes are the same. The exact drop in temperature can vary widely depending on other factors such as 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 hits the Earth in the fall. compared to summer.
A higher sun angle produces more intense sunlight and higher temperatures, and the angle begins to decrease in autumn.
The 2017 total solar eclipse took place during a summer afternoon in August, so temperatures were already high, making them more likely to form craters in some places along the path of totality. Temperatures dropped 11 degrees in just one hour in Douglas, Wyoming, and widespread temperature drops of 4 to 8 degrees occurred across the South.
Temperature drops during this Saturday’s eclipse are not expected to be as drastic, but they could still drop a few degrees on the path to annularity.
Areas that only experience 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 slower rise in temperatures could limit how high temperatures can rise in the afternoon hours and leave this Saturday a little cooler than if there were no eclipse. This can happen in Dallas and Phoenix, where the moon will block 80% of the sun.
An eclipse affects more than just the temperature. Less solar radiation and reduced temperatures can also affect wind, humidity and cloudiness.
Enthusiasts watch a total solar eclipse near Mitchell, Oregon, on August 21, 2017. (Adrees Latif/Archyde.com)
The rapid cooling during an eclipse briefly reduces the amount of heat stored in the atmosphere. The heat forces the air to rise and makes the atmosphere unstable. The atmosphere then creates clouds, storms, and wind to release thermal energy in an attempt to regain balance.
So, as the eclipse cools the air, the atmosphere calms down and the wind speed decreases because the atmosphere is not working as hard to balance itself. Scientists took a series of climate measurements in Wyoming and New York during the 2017 total solar eclipse and found that wind speeds decreased by an average of 6 mph as a result of the eclipse.
The humidity you feel is closely related to the temperature. Humidity increases when the air temperature and the dew point, which measures how much moisture is in the air, approach the same temperature. So when the air temperature drops briefly during an eclipse, it tends to move closer to the dew point and makes the air feel a little more humid.
A significant drop in temperature can also alter cloudiness.
Clouds over parts of South Carolina disappeared during the 2017 total solar eclipse because they lost their fuel: the heat that forces air to rise and form clouds. Some clouds may also dissipate in Saturday’s eclipse, even with less drastic temperature drops.
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