Enthusiasts watch the total solar eclipse near Mitchell, Oregon on August 21, 2017.
During a solar eclipse, the Moon passes in front of the Sun and casts a shadow on Earth’s surface, causing changes in temperature, wind speed, and humidity.
The more sunlight is blocked, the more dramatic the weather changes. It’s comparable to how shaded areas can be cooler on a hot day than anywhere in direct sunlight.
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 to reach the Earth’s surface – sunlight and energy – than a total eclipse that blocks the Sun completely.
But reductions in solar radiation, however brief, can affect temperatures and other weather conditions.
Not all eclipse weather changes are created equal. The exact drop in temperature varies widely based on the time of year and other factors such as cloud cover.
October’s annual eclipse is going to have a less dramatic effect on temperatures than August’s total eclipse, not only because of the amount of sun blocked by the moon, but also because of the lower angle at which the sun hits Earth in fall compared to summer. .
A higher solar angle produces more intense sunlight and higher temperatures, and the angle begins to decrease in autumn.
of 2017 Total solar eclipse It happened on a summer afternoon in August, so temperatures were already high, and there was a high chance of cratering somewhere along the path of totality. Temperatures fell 11 degrees in one hour in Douglas, Wyoming, and temperatures fell 4 to 8 degrees across the South.
People watch a solar eclipse approach totality from Great Smoky Mountains National Park in Tennessee on August 21, 2017.
Temperature drops during Saturday’s eclipse are not expected to be drastic, but could still drop a few degrees The path of the loop.
Areas experiencing only a partial solar eclipse could see a slow rise in temperatures from morning to afternoon, Juan Hernandez, a meteorologist with the National Weather Service in Fort Worth, Texas, told CNN.
A slower rise in temperatures could limit how far high temperatures can climb in the afternoon hours, and Saturday could be slightly cooler than without the eclipse. This can happen in Dallas and Phoenix, where the Moon will block 80% of the Sun.
An eclipse affects more than temperature. Less solar radiation and lower temperatures affect wind, humidity and cloud cover.
Rapid cooling during an eclipse briefly reduces the amount of heat stored in the atmosphere. Heat causes air to rise and make the atmosphere unstable. The atmosphere then releases heat energy in an attempt to bring itself back into balance, creating clouds, storms and winds.
As the eclipse cools the air, the atmosphere calms down and the wind speeds down because the atmosphere isn’t working as hard to balance itself. Scientists took several weather measurements in Wyoming and New York during the 2017 total solar eclipse. And found Wind speeds decreased by an average of 6 mph as a result of the eclipse.
How humid it feels is closely linked to temperature. Humidity rises as air temperature and the dew point, which measures how much moisture is in the air, approach the same temperature. So when air temperatures drop slightly during an eclipse, they approach the dew point and make the air feel a little more humid.
Substantial temperature drops can also change cloud cover.
Clouds disappeared in parts of South Carolina during 2017’s total solar eclipse because they ran out of fuel — the heat that causes air to rise and form clouds. Even with less severe temperature drops, a few clouds may disperse during Saturday’s eclipse.