6 Ways Humans Influence the Weather

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If you've ever spent any length of time on Twitter, you've probably heard a thing or two about humans secretly having the ability to control the weather. While that talent only exists in movies, we humans and our everyday activities do indirectly influence the weather in ways that go far beyond our production of greenhouse gases. Climate scientists and meteorologists have documented these effects for years. 

1. CITIES FORM HEAT ISLANDS.

sunlight shining through city streets and buildings
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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.

While the urban heat island effect might make you think of burning-hot asphalt, it's actually 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.

wheat crops growing in a field
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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. In 2016, Mesonet, a network of weather stations in Oklahoma, found that newly harvested areas of wheat in the northern part of the state were hotter and had a lower dew point than their cooler but muggier surroundings.

3. PAVING INCREASES THE INTENSITY OF FLOODS.

multilane highway with heavy traffic
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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.

nuclear power plant during the winter
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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.

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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.

plane exhaust in the sky with a foreground of bushes and trees
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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 leaves contrails, short for condensation trails, in its 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 the Arctic and Antarctic get cold enough that contrails can form at or near ground level.

Editor's note: This story, which originally ran in 2016, was updated in August 2018.

This Course Will Teach You How to Play Guitar Like a Pro for $29

BartekSzewczyk/iStock via Getty Images
BartekSzewczyk/iStock via Getty Images

Be honest: You’ve watched a YouTube video or two in an attempt to learn how to play a song on the guitar. Whether it was through tabs or simply copying whatever you saw on the screen, the fun always ends when friends start throwing out requests for songs you have no idea how to play. So how about you actually learn how to play guitar for real this time?

It’s now possible to learn guitar from home with the Ultimate Beginner to Expert Guitar Lessons Bundle, which is currently on sale for $29. Grab that Gibson, Fender, or whatever you have handy, and learn to strum rhythms from scratch.

The strumming course will teach you how to count beats and rests to turn your hands and fingers into the perfect accompaniment for your own voice or other musicians. Then, you can take things a step further and learn advanced jamming and soloing to riff anytime, anywhere. This course will teach you to improvise across various chords and progressions so you can jump into any jam with something original. You’ll also have the chance to dive deep into the major guitar genres of bluegrass, blues, and jazz. Lessons in jam etiquette, genre history, and how to read music will separate you from a novice player.

This bundle also includes courses in ear training so you can properly identify any relative note, interval, or pitch. That way, you can play along with any song when it comes on, or even understand how to modify it into the key you’d prefer. And when the time comes to perform, be prepared with skilled hammer-ons, pull-offs, slides, bends, trills, vibrato, and fret-tapping. Not only will you learn the basic foundations of guitar, you’ll ultimately be able to develop your own style with the help of these lessons.

The Ultimate Beginner to Expert Guitar Lessons Bundle is discounted for a limited time. Act on this $29 offer now to work on those fingertip calluses and play like a pro.

 

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A Prehistoric Great White Shark Nursery Has Been Discovered in Chile

Great white sharks used prehistoric nurseries to protect their young.
Great white sharks used prehistoric nurseries to protect their young.
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Great white sharks (Carcharodon carcharias) may be one of the most formidable and frightening apex predators on the planet today, but life for them isn’t as easy as horror movies would suggest. Due to a slow growth rate and the fact that they produce few offspring, the species is listed as vulnerable to extinction.

There is a way these sharks ensure survival, and that is by creating nurseries—a designated place where great white shark babies (called pups) are protected from other predators. Now, researchers at the University of Vienna and colleagues have discovered these nurseries occurred in prehistoric times.

In a study published in the journal Scientific Reports, Jamie A. Villafaña from the university’s Institute of Palaeontology describes a fossilized nursery found in Coquimbo, Chile. Researchers were examining a collection of fossilized great white shark teeth between 5 and 2 million years old along the Pacific coast of Chile and Peru when they noticed a disproportionate number of young shark teeth in Coquimbo. There was also a total lack of sexually mature animals' teeth, which suggests the site was used primarily by pups and juveniles as a nursery.

Though modern great whites are known to guard their young in designated areas, the researchers say this is the first example of a paleo-nursery. Because the climate was much warmer when the paleo-nursery was in use, the researchers think these protective environments can deepen our understanding of how great white sharks can survive global warming trends.