What Is the Dew Point, and How Does It Relate to Humidity?

iStock
iStock

Humidity has been a part of weather forecasts for as long as we’ve gotten our news over the air. At the beginning of most weather forecasts, our friendly neighborhood weatherperson tells us the sky conditions at the moment, the current temperature, and the relative humidity. Over the past couple of decades, though, the relative humidity has started to fall by the wayside in favor of the dew point. The dew point is a much more useful measure of how much moisture is in the air, but how does it relate to relative humidity?

The amount of water vapor in the air can dictate what kind of weather we see and how comfortable we are once we step outside. Relative humidity is technically defined as the air’s vapor pressure divided by its equilibrium vapor pressure. Equilibrium vapor pressure means that “there is no net evaporation or condensation,” according to Alistair Fraser, professor emeritus of meteorology at Penn State. At the equilibrium, otherwise known as the saturation point, water molecules are entering and leaving the condensed state at the same rate. When the relative humidity is cited as 50 percent, that means that the air is halfway to its saturation point, and that net evaporation is occurring. Warm air requires more water vapor than cool air to reach its saturation point, which is why an 85°F afternoon can get much muggier than a day that only makes it to 50°F—the latter can still be humid, sure, but it’s not like walking into a sauna.

The dew point is the temperature to which the air needs to cool down to in order to become completely saturated, or reach 100 percent relative humidity. Once the air temperature cools below its dew point, water vapor in the atmosphere will condense. This causes the relative humidity to go up and down like a roller coaster during the day. The relative humidity will go up at night when the air temperature approaches the dew point, and the relative humidity will go down as the air temperature warms farther and farther away from the dew point during the day.

The dew point is a little more abstract than the relative humidity, but it’s an effective way of telling you how much moisture is present in the air because it means the same thing no matter how warm or cold it is outside. A 40°F dew point is comfortable whether the air temperature is 60°F or 100°F. This consistency allows us to index the dew point to comfort levels, giving us a quick understanding of how muggy or pleasant it is outside.

It’s downright dry outside when the dew point is at or below the freezing point. Dew point readings between the freezing mark and about 55°F are pretty comfortable. A dew point between 55°F and 60°F is noticeably humid. It’s muggy when the dew point is above 60°F, and it’s uncomfortable outside when it ticks above 65°F. Any dew point readings above 70°F are oppressive and even dangerous, the kind of stickiness you experience in the tropics or during a brutal summer heat wave. It’s rare for the dew point to reach 80°F, but it can happen in extremely moist areas like corn fields or certain tropical areas.

The dew point and relative humidity are closely related, but the former is much more useful than the latter. Relative humidity helps meteorologists predict conditions favorable for wildfires and fog. Other than that, it’s mostly a relic of the old days that show up in weather reports out of habit. If you want to know the true measure of how comfortable or muggy it is outside, take a look at the dew point.

The ChopBox Smart Cutting Board Has a Food Scale, Timer, and Knife Sharper Built Right Into It

ChopBox
ChopBox

When it comes to furnishing your kitchen with all of the appliances necessary to cook night in and night out, you’ll probably find yourself running out of counter space in a hurry. The ChopBox, which is available on Indiegogo and dubs itself “The World’s First Smart Cutting Board,” looks to fix that by cramming a bunch of kitchen necessities right into one cutting board.

In addition to giving you a knife-resistant bamboo surface to slice and dice on, the ChopBox features a built-in digital scale that weighs up to 6.6 pounds of food, a nine-hour kitchen timer, and two knife sharpeners. It also sports a groove on its surface to catch any liquid runoff that may be produced by the food and has a second pull-out cutting board that doubles as a serving tray.

There’s a 254nm UVC light featured on the board, which the company says “is guaranteed to kill 99.99% of germs and bacteria" after a minute of exposure. If you’re more of a traditionalist when it comes to cleanliness, the ChopBox is completely waterproof (but not dishwasher-safe) so you can wash and scrub to your heart’s content without worry. 

According to the company, a single one-hour charge will give you 30 days of battery life, and can be recharged through a Micro USB port.

The ChopBox reached its $10,000 crowdfunding goal just 10 minutes after launching its campaign, but you can still contribute at different tiers. Once it’s officially released, the ChopBox will retail for $200, but you can get one for $100 if you pledge now. You can purchase the ChopBox on Indiegogo here.

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Snow Kidding: A Polar Vortex Could Hit the Eastern U.S. This Month

You may not want to put your ice scraper away just yet.
You may not want to put your ice scraper away just yet.
Tamara Dragovic/iStock via Getty Images

If you’re in the eastern U.S. and planning some gardening sessions, you might want to double-check the forecast. According to the Washington Post, a polar vortex like the one that hit the U.S. in 2019 is lurking and prepared to unleash chilly air in the eastern half of the country. Some areas can even expect snow—in Pennsylvania, maybe as much as an inch.

Powder is expected in the Northeast and Mid-Atlantic areas, with cool temperatures spreading from the Upper Midwest to New England, which might see a topcoat of snow beginning this weekend. Georgia might get some frost. The cold front could experience 20-degree reductions in temperatures, with Minneapolis dropping into the upper 40s and Chicago seeing 45°F.

Areas like Providence, Rhode Island; Hartford, Connecticut; and Boston—normally in the 60s this time of year—might not climb out of the 40s over the weekend. New York City, which has been enjoying temperatures in the 70s, won’t get out of the 50s.

Blame the peculiar weather on the polar vortex, which may be best described as an arctic hurricane that transports freezing air south when warm weather pushes it out of northern Canada, Alaska, or Greenland. In other words: There’s no rush on installing that air conditioner just yet.

[h/t Washington Post]