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NASA Figures Out Why When It Rains, It (Sometimes) Drizzles

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What’s the difference between drizzle and rain? It has to do with updrafts, according to new research by NASA scientists into the previously unexplained phenomenon of why drizzle occurs where it does.

The answer, published in the Quarterly Journal of the Royal Meteorological Society, could help improve how weather and climate models treat rainfall, making predictions more accurate.

Previously, climate researchers thought that drizzle could be explained by the presence of aerosols in the atmosphere. The microscopic particles are present in greater quantities over land than over the ocean, and by that logic, there should be more drizzle over land than over the ocean. But that's not the case, as Hanii Takahashi and her colleagues at the Jet Propulsion Laboratory found. Instead, whether or not rain becomes full droplets or stays as a fine drizzle depends on updrafts—a warm current of air that rises from the ground.

Stronger updrafts keep drizzle droplets (which are four times smaller than a raindrop) floating inside a cloud longer, allowing them to grow into full-sized rain drops that fall to the ground in the splatters we all know and love. In weaker updrafts, though, the precipitation falls before the drops form, as that light drizzle. That explains why it drizzles more over the ocean than over land—because updrafts are weaker over the ocean. A low-lying cloud over the ocean is more likely to produce drizzle than a low-lying cloud over land, which will probably produce rain.

This could have an impact on climate modeling as well as short-term weather forecasts. Current models make it difficult to model future surface temperatures of the Earth while still maintaining accurate projections about the amount of precipitation. Right now, most models that project realistic surface temperatures predict an unrealistic amount of drizzle in the future, according to a NASA statement. This finding could bring those predictions back down to a more realistic level.

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Weather Watch
It Just Snowed In the Sahara for the Second Time In Less Than a Month
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The town of Aïn Séfra, Algeria might need to find a new nickname. Though it’s often referred to as “The Gateway to the Sahara,” the 137-year-old province in northwest Algeria is currently digging out from a rare—and unexpected—snowstorm that left the desert town covered in several inches of snow and battling sub-zero temperatures.

While the Daily Mail reported that “locals took to the nearby sand dunes to enjoy the unusual weather,” the strangest part of the story is that this is Aïn Séfra’s second snowfall in less than a month. On Sunday, January 7, a freak blizzard left parts of the Sahara blanketed in as much as 16 inches of snow.

This most recent storm marked the region’s fourth snowfall in nearly 40 years; in addition to January's dose of the white stuff, the area has been hit with other surprise wintry events in February 1979 and December 2016.

But North Africa isn’t the only area that’s seeing record-breaking weather events. On Saturday, February 3, 17 inches of snow fell on Moscow within 24 hours in what the country has dubbed “the snowfall of the century.” In mid-January, Oymyakon, Russia—a rural village in the Yakutia region, which is already well known as one of the coldest inhabited areas of the world—saw temperatures drop to -88.6°F, making it chilly enough to both bust thermometers and freeze people’s eyelashes. And you thought dealing with single-digit temperatures was tough!

[h/t: Daily Mail]

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Weather Watch
Record-Breaking 17 Inches of Snow Covers Moscow in 24 Hours
Vasily Maximov, AFP/Getty Images
Vasily Maximov, AFP/Getty Images

Moscow sees some of the most brutal winters of any world capital, but even locals weren't prepared for the most recent winter storm to batter the city. As Newsweek reports, a record-breaking 17 inches of snow buried Moscow within 24 hours.

Roughly 7 inches of snow fell just on Saturday, February 3, and the deluge continued through the following Sunday. The accumulation has already been dubbed the "snowfall of the century," and officials expect up to 3 additional inches to cover the ground over the next three days.

The sudden blizzard has brought life to a stand-still in the metropolis of 12 million. The mayor is warning motorists to stay off the roads as around 15,000 snowplows clear the snow. About 2000 trees have been toppled by the storm, injuring at least five people and killing one.

Even as the worst of the weather winds down, over 40,000 people in Moscow and the surrounding regions are without power. Meanwhile, traveling in and out of the city has become close to impossible: Around 100 flights are grounded at the local airport indefinitely and at least 10 have been canceled all together.

The historic snowfall hasn't stopped many of Moscow's tougher residents from venturing outside. Check out photos from the event below.

Person cross-country skiing over snow in Moscow.
Yuri Kadobnov, AFP/Getty Images

Walking through a blizzard in Moscow.
Yuri Kadobnov, AFP/Getty Images

Walking through the snow in Moscow.
Yuri Kadobnov, AFP/Getty Images

Walking through the snow in Moscow.
Yuri Kadobnov, AFP/Getty Images

[h/t Newsweek]

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