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6 Ways Humans Influence the Weather

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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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Last Month Was the Second-Warmest October on Record
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After an unseasonably toasty October, the numbers are in: Temperatures exceeded averages across the globe last month, making it the second-hottest October ever recorded, according to NASA.

As Mashable reports, worldwide temperatures reached 1.62°F (or 0.90°C) above the average in October. It just edged out global temperatures in October 2016 and came short of the all-time October record set in 2015. But while El Niño contributed to temperature spikes in 2015, there's no weather event to explain the anomaly this time around.

Records of global mean surface temperature changes date back to 1880. Of the 136 years in NASA’s database, the past three years (2014, 2015, 2016) have produced the greatest temperature anomalies. With the end of the year approaching, it looks like 2017 will end up breaking into the top three, and will likely be the warmest non-El Niño year on record.

While alarming, the record-breaking statistics shouldn't be surprising to anyone who follows global climate trends. The Earth has been warming at a rapid rate in recent decades, and climate scientists blame the carbon dioxide being dumped into the atmosphere by human activity.

Following a hot autumn, the next few months aren't looking to be any cooler: Like last winter and the winter before that, this season is expected to be unusually warm.

[h/t Mashable]

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This Just In
How One New York Town Is Preparing for the Next Hurricane Sandy
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Darren McCollester, Stringer, Getty Images

This past Sunday marked five years since Hurricane Sandy made landfall over the northeastern U.S. While the towns hit hardest by the storm are using the time as an opportunity to reflect on the lives, homes, and landscapes that were destroyed, they’re also continuing to prepare for the next mega-storm that will reach their shores. One beach town in Staten Island, New York is investing in a strategy that’s especially innovative: As Mother Jones reports, the surge barrier that’s being erected off the shores of Tottenville will repurpose nature to provide protection from natural disasters.

The government-funded project, called Living Breakwaters, is the brainchild of MacArthur Genius and landscape architect Kate Orff. Rather than building a conventional seawall, Orff and her firm envision a “living piece of infrastructure” containing an oyster reef that will continue to grow and respond to its environment even after construction ends. During a harsh storm, the breakwater would absorb the impact of dangerous waves barreling toward shore. It also has the potential to preserve the environment in the long term by decreasing erosion and wave activity.

Because Living Breakwaters is designed to act as part of its environment, it offers a few benefits in addition to flood protection. The creatures that make their homes on the reef will eventually purify the waters around them and make the shores of Tottenville cleaner and healthier. The reef will also be more discreet and pleasing to look at than a harsh concrete wall, meaning Tottenville residents can enjoy their clear ocean views without having to sacrifice safety.

The project is still in its preliminary stages, with construction scheduled to start in 2019 and wrap up in 2021. Rather than relying entirely on an experimental method, the community is integrating the breakwaters into a larger flood protection plan. Some tools, like wave-blocking sand dunes, will also take advantage of the area’s natural resources.

[h/t Mother Jones]

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