Will the Solar Eclipse Have an Impact on the Weather?

The United States will have a front-row seat to one of the most spectacular solar eclipses to sweep across the country in our lifetimes. Millions of lucky observers from coast to coast will have the chance to watch the Moon scoot in front of the Sun on the afternoon of August 21, 2017, briefly plunging cities like Salem, Oregon, Hopkinsville, Kentucky, and Columbia, South Carolina, into night-like darkness during the day. Read our field guide to the solar eclipse for tips on how to make the most of this spectacular event.

While a solar eclipse can be amazing to behold, the phenomenon has little impact on Earth. It may, however, have a small but noticeable effect on weather in the areas that experience a total eclipse.

The entire country will be able to see the Moon cover the Sun in some form, but the best viewing areas will be along a northwest-to-southeast path across the middle of the country. According to NASA, a location needs at least 90 percent coverage to notice any darkening at all, and even 99 percent coverage of the Sun only provides the same level of darkness you'd see at twilight. Areas totally covered by the Moon's relatively narrow shadow will experience conditions akin to dusk, prompting street lights to turn on and even tricking birds and bugs into thinking that the day is drawing to an end. Studies have shown that the total eclipse could also have an effect on temperatures and even winds.

Researchers who studied an eclipse across Europe in 1999 found that the event lowered air temperatures by as much as 5°F across the path of totality. This brief dip in air temperatures also affected local wind speed and direction—not by much, but it was enough for both people and instruments to take notice of the so-called "eclipse wind." The effect on the atmosphere in Europe wasn't a fluke. A weather station in Zambia recorded a temperature drop of nearly 15°F during a solar eclipse in June 2001, and there are reports through history of observers noticing a distinct cooling effect in the midst of a lunar shadow.

The duration of the eclipse and the amount of moisture in the air will determine how much the Moon's shadow will lower temperatures. Moist air has a higher heat capacity than drier air, so when it's muggy outside it takes longer for the air to warm up and cool down. This is why daily temperatures fluctuate less in Miami, Florida, than they do in Phoenix, Arizona. Communities that lie among the drier, cooler Rocky Mountains are more likely to witness a noteworthy dip in temperatures compared to states like Tennessee or South Carolina, which are typically locked in the humid doldrums of summer at the end of August.

If you're lucky enough to witness this spectacular astronomical phenomenon, make sure you bring your eclipse glasses—and a thermometer.

What Is a Bomb Cyclone?

Maddie Meyer/Getty Images
Maddie Meyer/Getty Images

The phrase bomb cyclone has re-entered the news this week as parts of the central U.S. face severe weather. Mountain and Midwestern states, including Colorado, Nebraska, Wyoming, and South Dakota, all fall in the path of a winter storm expected to deliver tornadoes, hail, heavy snow, flooding, and hurricane-force winds on Wednesday, March 13 into Thursday. It seems appropriate for a storm that strong to have bomb in its name, but the word actually refers to a meteorological phenomenon and not the cyclone's explosive intensity.

According to The Denver Post, the bomb in bomb cyclone stands for bombogenesis. Bombogenesis occurs when a non-tropical storm experiences at least a 24 millibar (the unit used to measure barometric pressure) drop within 24 hours. Low pressure makes for intense storms, so a bomb cyclone is a system that's built up a significant amount strength in a short length of time.

This type of storm usually depends on the ocean or another large body of water for its power. During the winter, the relatively warm air coming off the ocean and the cold air above land can collide to create a sharp drop in atmospheric pressure. Also known as a winter hurricane, this effect has produced some of the worst snowstorms to ever hit the U.S.

The fact that this latest bomb cyclone has formed nowhere near the coast makes it even more remarkable. Rather, a warm, subtropical air mass and a cold, Arctic air mass crossed paths, creating the perfect conditions for a rare bombogenesis over the Rockies and Great Plains states.

Central U.S. residents in the bomb cyclone's path have taken great precautions ahead of the storm. Over 1000 flights have been canceled for Wednesday and schools throughout Colorado have closed.

[h/t The Denver Post]

Watch a Rare ‘Ice Tsunami’ Slam Lake Erie

Clean Lakes Alliance, Flickr // CC BY 2.0
Clean Lakes Alliance, Flickr // CC BY 2.0

A combination of freezing cold temperatures and high winds is creating an unusual phenomenon along Lake Erie. As KDKA reports, ice tsunamis are toppling onto lake shores, and many locals have been asked to stay inside and even evacuate their homes.

On February 24, 2019, the National Weather Service in Buffalo, New York issued a warning about dangerous wind gusts in the Lake Erie area. The service urged citizens to seek shelter indoors and avoid traveling if possible. Winds peaked at 74 mph earlier this week, the level of a Category 1 hurricane, and tore down trees and power lines throughout the region.

People who got close to Lake Erie during the windstorm witnessed a rare event known as an ice tsunami. When wind pushed ice on the lake's surface toward the retaining wall, the sheet broke apart and dumped massive ice chunks on the shore. The video below captures the phenomenon.

In some areas, the ice piles grew so large that roadways had to be closed. Residents of Hamburg, New York's Hoover Beach area were asked to voluntarily evacuate due to the encroaching ice.

Ice tsunamis, or ice shoves, are rare, but in some cases they can be life-threatening. In 2013, waves of ice shards from a Minnesota lake destroyed people's homes.

[h/t KDKA]

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