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.

Storm Leaves Homes Along Lake Erie Covered in Up To Three Feet of Ice

Houses along Lake Erie's shoreline were pummeled with sheets of icy water during a storm last week.
Houses along Lake Erie's shoreline were pummeled with sheets of icy water during a storm last week.
John Normile/Getty Images

This past weekend, lakeside residents of Hamburg, New York, awoke to find their neighborhood transformed into a full-scale replica of Frozen’s ice-covered kingdom, Arendelle.

According to CNN, gale force winds produced giant waves that sprayed the houses along Lake Erie with sheets of water for two days straight, covering them in layers of ice up to three feet thick.

“It looks fake, it looks surreal,” Hamburg resident Ed Mis told CNN. “It’s dark on the inside of my house. It can be a little eerie, a little frightening.”

While the homeowners are anxious for the ice to melt, they’re also concerned about what could happen when it does.

“We’re worried about the integrity, of structure failure when it starts to melt, because of the weight on the roof,” Mis said.

He added that this is the worst ice coating he’s seen since he moved to the area eight years ago—but it’s not because they’ve had a particularly harsh winter. In fact, just the opposite is true. According to The Detroit News, warm winter temperatures have caused ice cover on the Great Lakes to drop from 67 percent in 2019 to less than 20 percent this year.

“Lake Erie typically has significant ice cover by this time of the year, and that protects the shoreline from these battering storms,” The Weather Channel’s winter weather expert Tom Niziol explained in a video.

The phenomenon has created another unforeseen issue for Hamburg’s coast, too: Tourism. The local police department posted a message on Facebook on Sunday, March 1, asking people to keep off both the “extremely unsafe and unstable” ice and people's private property.

[h/t CNN]

What is Lake-Effect Snow?

Tainar/iStock via Getty Images
Tainar/iStock via Getty Images

As you probably guessed, you need a lake to experience lake-effect snow. The primary factor in creating lake-effect snow is a temperature difference between the lake and the air above it. Because water has a high specific heat, it warms and cools much more slowly than the air around it. All summer, the sun heats the lake, which stays warm deep into autumn. When air temperatures dip, we get the necessary temperature difference for lake-effect snow.

As the cool air passes over the lake, moisture from the water evaporates and the air directly above the surface heats up. This warm, wet air rises and condenses, quickly forming heavy clouds. The rate of change in temperature as you move up through the air is known as the "lapse rate"; the greater the lapse rate, the more unstable a system is—and the more prone it is to create weather events.

Encountering the shore only exacerbates the situation. Increased friction causes the wind to slow down and clouds to "pile up" while hills and variable topography push air up even more dramatically, causing more cooling and more condensation.

The other major factors that determine the particulars of a lake-effect snowstorm are the orientation of the wind and the specific lake. Winds blowing along the length of a lake create greater "fetch," the area of water over which the wind blows, and thus more extreme storms like the one currently pummeling the Buffalo area. The constraints of the lake itself create stark boundaries between heavy snow and just a few flurries and literal walls of snow that advance onto the shore. The southern and eastern shores of the Great Lakes are considered "snow belts" because, with winds prevailing from the northwest, these areas tend to get hit the hardest.

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