Kristian Dowling/Getty Images
Kristian Dowling/Getty Images

There's No Such Thing as 'the Temperature in the Shade'

Kristian Dowling/Getty Images
Kristian Dowling/Getty Images

We’re getting into that stretch of the summer when in much of the world it’s downright miserable to sit near a window, let alone go outside and let the Sun beat down on us. Pretty soon we’ll start to hear people exclaim that it’s 100°F in the shade. Talking about “the temperature in the shade” lets us emphasize how hot it is outside while also pointing out how hot it feels when you’re not in the shade. But meteorologically speaking, there is no such thing as the temperature in the shade. That’s just the actual air temperature.

When you look at a weather report during the summer, you typically see three readings reported: air temperature, dew point, and the heat index. The dew point is the temperature at which the air would reach 100 percent humidity, which is the best way to measure how muggy it is outside. The heat index is what it feels like to your body when you combine both the temperature and the dew point—a heat index of 110°F, for instance, means that the current air temperature plus the humidity has the same effect on your body as an actual air temperature of 110°F.

Bring your own shade, as these women knew to do in 1939 London when they donned their Dolly Varden Sun Bonnets, which consisted of a large non-inflammable eye shade and a georgette tie. Image credit: George W. Hales/Fox Photos/Getty Images

Direct sunlight makes those unbearable temperatures even worse. If you’ve ever seen a thermometer exposed to direct sunlight on your deck or vehicle, you know what I mean—even if the actual air temperature is only 90°F, the thermometer bathing in the sun will read dozens of degrees higher, sometimes hotter than the hottest natural temperature ever recorded (134°F in Death Valley, California, in 1913). That’s not the real temperature, of course; it’s the temperature of the air combined with the temperature of the sensor itself warming up in the sunlight.

Thermometers used in official weather stations maintained by airports and weather agencies around the world are built with plastic or wooden shelters around them to prevent contamination from sunlight. The enclosure that surrounds the thermometer allows the sensor to measure the actual air temperature; in other words—drum roll—the temperature in the shade.

Even though “the temperature in the shade” is little but hyperbole, the sun really does have an impact on your body beyond a painful sunburn. Just like your deck thermometer, standing out in broad daylight on a blistering day can make your body have to work much harder than it already does—potentially to the point that you can get sick. That 90°F temperature is already made worse by humidity (preventing your sweat from cooling you off), but standing in the sun heats up your skin and your clothes even more, making it harder to cool off unless you find air conditioning or cover from the sun.

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Drought Reveals Ancient Sites in Scotland That Can Only Be Spotted From the Air
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iStock

Typically rainy Scotland is in the middle of an unusually dry summer—and local archaeologists are taking advantage of it. As the BBC reports, the drought has revealed ancient sites, including Roman camps and Iron Age graves, that have been hidden by farm soil for years.

Historic Environment Scotland has been conducting aerial surveys of the country's landscape since the 1930s, but it's in seasons like this, when the crops recede during dry weather, that the buried remains of ancient structures are easiest to spot. Conditions this summer have been the best since 1976 for documenting archaeological sites from the sky.

Aerial view of field.
Historic Environment Scotland

The crescent-shaped crop mark in the photo above indicates a souterrain, or underground passageway, that was built in the Scottish Borders during the Iron Age. The surveyors also found remains of a Roman temporary camp, marked by straight lines in the landscape, built in modern-day Lyne—an area south of Edinburgh already known to have housed a complex of Roman camps and forts.

Aerial view of field.
Historic Environment Scotland

In the image below you'll see four small ditches—three circles and one square—that were likely used as burial sites during the Iron Age. When crops are planted over an ancient ditch, they have more water and nutrients to feed on, which helps them grow taller and greener. Such crops are especially visible during a drought when the surrounding vegetation is sparse and brown.

Aerial view of field.
Historic Environment Scotland

Historic Environment Scotland has a team of aerial surveyors trained to spot the clues: To date, they've discovered more than 9000 archaeological sites from the air. HSE plans to continue scoping out new areas of interest as long as the dry spell lasts.

It's not just in Scotland that long-hidden settlements are coming to light: similar aerial surveys in Wales are finding them too.

[h/t BBC]

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Heatwaves Can Affect Your Ability to Think Clearly and Make Decisions
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iStock

Dehydration and body odor aren't the only things to hate about oppressive heat. According to new research reported by The Guardian, living through a heatwave without relief hampers your ability to think quickly and clearly.

For their study, published recently in PLOS Medicine, researchers at the Harvard T.H. Chan School of Public Health tested the mental performance of 44 students during a heatwave in Boston in 2016. Roughly half the students were living in newer dorm buildings with central AC, with the other half living in older dorms without it.

Over 12 days, researchers had participants take cognition tests on their phones immediately after waking up. The students living without AC took about 13 percent longer to respond to the questions and their answers were about 13 percent less accurate.

The results indicate that even if high temperatures don't pose an immediate threat to someone's health, they can impair them in other ways. “Most of the research on the health effects of heat has been done in vulnerable populations, such as the elderly, creating the perception that the general population is not at risk from heat waves,” Jose Guillermo Cedeño-Laurent, research fellow at Harvard Chan School and lead author of the study, said in a statement. “Knowing what the risks are across different populations is critical considering that in many cities, such as Boston, the number of heat waves is projected to increase due to climate change.”

Summers are gradually becoming hotter and longer in Boston—a trend that can be observed throughout most of the rest of the world thanks to the rising temperatures caused by human activity. In regions with historically cold winters, like New England, many buildings, including Harvard's oldest dorms, are built to retain heat, which can extend the negative effects of a heat wave even as the weather outside starts to cool. If temperatures continue to rise, we'll have to make a greater effort to keep people cool indoors, where American adults spend 90 percent of their time.

Our thinking isn't the only thing that suffers in the stifling heat. A study published last year found that hot weather does indeed make you crankier—which may not be as bad as bombing a test, but it's not exactly not fun for the people around you.

[h/t The Guardian]

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