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6 Ways Humans Influence the Weather

Girls eat popsicles and cool off in a Tokyo park during a 2014 heat wave. Image credit: Yoshikazu Tsuno/AFP/Getty Images

If you’ve ever spent any length of time on Twitter or talking to friends from northern California, you’ve probably heard a thing or two about humans secretly having the ability to control the weather. While we don’t have the capability to control the weather outside of the movies, we humans and our everyday activities really are able to indirectly influence the weather in ways that go far beyond our addiction to greenhouse gases.

1. CITIES FORM HEAT ISLANDS. 

They’re not exactly wrong when they call the capital of Georgia “Hotlanta.” Most populated areas generate heat simply by existing. The dense web of asphalt roads, concrete sidewalks, brick facades, and tar roofs are able to absorb a significant amount of heat from the daytime sun, even in the dead of winter. This human-made insulation, called the urban heat island effect, keeps city centers a tad hotter on hot days and a little less cool on cold days.

The urban heat island effect is most noticeable during winter storms when air temperatures are hovering right around freezing, putting you right on the line between wet snow, an icy mix, or a cold rain. The artificial warmth from cities can influence the precipitation type in these storms, potentially lowering a city’s snow accumulations compared to its suburbs.

A 2011 study published in the Journal of Applied Meteorology and Climatology [PDF] also found that the urban heat island effect can have a pronounced impact on thunderstorms that form over cities. The researchers studied 91 summertime thunderstorms that formed over Indianapolis, Indiana, and found that their research models could not replicate those thunderstorms without the influence of the urban area beneath the storms.

2. CROPS JACK UP THE HUMIDITY. 

If cities can absorb the heat of the day and make it even hotter, you can imagine how the vast swaths of crops that blanket the countryside can also affect our daily weather. Instead of making it hotter, crops can make a humid day unbearable by sending moisture levels almost off the charts on a putrid summer’s day.

Corn crops are notorious for pushing dew points—the temperature at which the air reaches 100 percent humidity—up above 80°F in the middle of the summer, creating a dangerous heat index that soars far above 100°F. Compare that to a muggy day, which has a dew point around 70°F, or a comfortably dry day with a dew point in the low 50s.

The harvest can have the opposite effect, as seen in northern Oklahoma this summer when farmers harvested their winter wheat crops. The state’s Mesonet, a network of weather stations, found that the newly harvested areas were hotter and had a lower dew point than their cooler but muggier surroundings.

3. PAVING INCREASES THE INTENSITY OF FLOODS.

Vehicles left stranded on a flooded Interstate 45 in Houston, Texas on May 26, 2015. Image credit: Aaron M. Sprecher/AFP/Getty Images 

Our obsession with construction doesn’t stop at influencing temperatures. Paving over porous earth with relatively impervious materials like asphalt and concrete has also had a major impact on flooding during heavy rain events. Fewer places for rainwater to escape means that the sudden influx of water builds up in urban areas or runs off and inundates places that had never seen flooding before.

4. NUCLEAR POWER PLANTS CAN TRIGGER NUCLEAR-EFFECT SNOW.

Lake effect snow is a yearly phenomenon across North America’s Great Lakes, where bitterly cold air flows over the warm lake water, triggering convection that blows ashore as heavy bands of snow. The bands of snow are so intense that communities can see many feet of snow in one day, sometimes accompanied by thunder and lightning.

It’s not only bodies of water that can cause this phenomenon. Nuclear power plants release large amounts of steam during the course of their operations, and on cold mornings when there’s enough moisture in the air, locations immediately downwind of a power plant’s steam stacks can experience “nuclear-effect snow,” which forms through similar means as lake effect snow. The phenomenon isn’t limited to just nuclear power plants, but they produce enough steam that it’s noticeable over a large area. Thankfully for residents nearby, it doesn’t produce much snow—and it’s not radioactive.  

5. URBAN DENSITY CAN AMPLIFY WINDS.  

The robes of Pope Francis are blown over his head by a gust of wind in St. Peter's Square in Vatican City. Image credit: Franco Origlia/Getty Images

If you’ve ever walked down a city street on a windy day, you’ve probably noticed that it sometimes feels like you’re being buffeted by air shot out of an industrial fan instead of a regular windstorm. Dense building construction can amplify the winds and cause gusts to blow much faster than they would out in the open. This wind tunnel effect can cause serious damage, blowing out windows, knocking down trees, and sending dangerous debris hurtling toward the busy streets below.

The principle is the same as holding your thumb over the end of a garden hose to make the water spray out faster—the wind speeds up dramatically as it presses between the buildings. This is also why you should never take shelter underneath a bridge during a tornado. The tornadic winds squeezing underneath the bridge will speed up, increasing the odds that you’ll be pelted by debris or sucked out into the open.

6) JETS CREATE CIRRUS CLOUDS.

The simple act of flying can also create intricate patterns of clouds in the sky that wouldn’t have formed had we not perfected the art of air travel. The hot water vapor produced by the engine exhaust of a high-flying jet aircraft leave contrails, short for condensation trails, in their wake. Contrails can dissipate right away or linger for hours depending on upper-level humidity and winds. These man-made cirrus clouds are most common at high cruising altitudes, but places like Arctic and Antarctic get cold enough that contrails can form at or near ground level. 

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MegaSecur, YouTube
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Design
The Self-Deploying Flood Barrier That Could Keep Cities Dry Without Sandbags
MegaSecur, YouTube
MegaSecur, YouTube

For many places in the world, the future is going to be wet. Climate change is already intensifying heavy rains and flooding in parts of the U.S., and it’s only expected to get worse. A recent study estimated that by 2050, more than 60 million people in the U.S. would be vulnerable to 100-year floods.

Some cities plan to meet rising waters with protective parkland, while some architects are developing floating houses. And one company has figured out how to replace piles of sandbags as emergency flood control, as Business Insider reports. Water-Gate, a line of flood protection products made by a Canadian company called MegaSecur, is a self-deploying water barrier that can be used to stop overflowing water in its tracks.

The emergency dam is made of folded canvas that, when water rushes into it, inflates up to become a kind of pocket for the water to get trapped in. You can roll it out across a street, a canal, or a creek like a giant hose, then wait for the water to arrive. In the event of a flash flood, you can even deploy it while the flood is already in progress. It can stop waters that rise up to five feet.

According to MegaSecur, one Water-Gate dam can replace thousands of sandbags, and once the floodwaters have receded, you can fold it back up and use it again. Sadly, based on the flood projections of climate change scientists, heavy flooding will soon become more and more common, and that will make reusable flood barriers necessary, saving time and money that would otherwise be spent buying, stacking, and getting rid of sandbags. The auto-deployment also means that it can be used by a single person, rather than a team of laborers. It could just as easily be set up outside a house by a homeowner as it could be set up on a city street by an emergency worker.

As climate change-related proposals go, it sounds a little more feasible than a floating house.

[h/t Business Insider]

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Weather Watch
Thanks to Desert Dust, Eastern Europe Is Covered in Orange Snow
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iStock

Certain areas of Eastern Europe are starting to look a bit like Mars. Over the last few days, snowy places like Sochi, Russia have experienced an unusual snowfall that coated mountains in orange powder, according to the BBC.

The orange snow was the result of winds blowing sand from the Sahara east to places like Moldova, Romania, Bulgaria, Ukraine, and Russia. The sand mixes with precipitation to form orange-tinted snow. According to the BBC, the phenomenon occurs semi-regularly, turning snow orange about once every five years, but this year is especially sandy. As a result, skiers are navigating slopes that look like they're from a different world, as you can see in the video below from The Guardian.

The Sahara rarely gets snow, but when it does, the landscape can look somewhat similar, as you can see in this image of the Atlas mountains in Morocco.

Instagram is currently filled with photos and videos from Eastern Europe featuring the odd-looking snow. Check out a few samples below.

[h/t BBC]

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