5 Weird But Real Weather Events

This scene was caused by a tanker full of mackerel spilling on a Belfast street in 2015, but a fish rain might look similar.
This scene was caused by a tanker full of mackerel spilling on a Belfast street in 2015, but a fish rain might look similar.
Charles McQuillan/Getty Images

We don’t remember most of the weather we experience on a daily basis. Even hardcore weather geeks are hard-pressed to recall many events beyond what reporters would cover on the news. But there are some atmospheric tantrums that are memorable because of how bizarre they are. Here are some true-yet-bizarre weather phenomena that you'd be sure to remember if you ever got to experience them firsthand.

1. WEIRDNESS: RAINS OF FROGS AND FISH. CAUSE: TORNADOES

Tornadoes can do some weird things. A tornado can destroy one house while leaving the house next door seemingly untouched. They can grow miles wide or last for just a couple of seconds. But one of the weirdest things about tornadoes is that they can actually make it rain aquatic creatures. If a tornado passes over a body of water like a lake, river, or pond, the extreme suction can lift fish and frogs right out of the water. What goes up must come down, and sometimes there are people in the way to tell the story after the skies clear out.

The Library of Congress reports that fish fell on a town in Louisiana back in 1947 after a rambunctious storm. Halfway around the world, a tornado caused "thousands of frogs" to rain from the sky on a town in Serbia in 2005.

2. WEIRDNESS: HEAT BURSTS AT NIGHT. CAUSE: THUNDERSTORMS

The Sun going down on a hot day usually robs thunderstorms of the instability they need to survive, ending the day's rumbling thunder and heavy rain not long after dark. However, some thunderstorms don't go out quietly. Folks on the American Plains have to deal with heat bursts every once in a while. If a layer of dry air develops within a dissipating thunderstorm, the rain falling out of the storm can evaporate all at once. The evaporating rain creates a bubble of cool, dense air that rushes toward the ground. This bubble of descending air compresses as it falls, causing it to dramatically warm up before crashing into the ground.

Alva, Oklahoma, recently experienced one of these heat bursts. The temperature there at 7:00 p.m. on June 15, 2017, was a balmy 90°F with thunderstorms in the area. By 8:00 p.m., the temperature dramatically rose to 96°F, and it peaked at 99°F by 8:20 p.m.. The sudden rise in temperature was accompanied by 20 to 30 mph winds and a sharp drop in humidity. Temperatures returned to normal by 9:30 p.m. Some heat bursts are even more dramatic, briefly raising temperatures above 100°F even in the middle of the night.

3. WEIRDNESS: PLANES THAT CAN'T FLY. CAUSE: INTENSE HEAT

Weather is the cause of most flight delays and cancellations in the United States. Whether conditions are too extreme for safe flying or rain and clouds just slow things down, it's never fun to have to fly when there's a big weather system rolling through. Sometimes even clear skies and bright sunshine can cancel flights. Phoenix, Arizona, recently made the news for their record-breaking heat wave canceling flights at the city's major airport.

Temperatures rose as high as 120°F in Phoenix, preventing some flights from safely landing or departing. Since hot air is less dense than cold air, extreme heat can prevent certain airplanes from generating the lift they need to safely take flight. If these airplanes try to take off in excessively high temperatures, the airplane runs the risk of barreling off the end of the runway before it could lift off.

4. WEIRDNESS: WET CYCLONES ON DRY LAND. CAUSE: POSSIBLY "BROWN OCEAN EFFECT"

Tropical cyclones usually fall apart once they make landfall. These swirling storms gather their energy from the heat given off by warm ocean waters; once that source of warmth runs out, the thunderstorms around the eye of the cyclone fizzle out and the storm starts weakening. Not all storms immediately fall apart once they hit land, though. Recent studies suggest that there's a "brown ocean effect," where warm, moist soil can serve as a substitute for warm ocean water, helping cyclones stay alive a little longer over land.

The southern United States saw a great example of this not too long ago. Tropical Storm Erin made landfall in Texas in August 2007 as a weak storm with 40 mph winds. Erin made its way inland and unexpectedly strengthened over Oklahoma three days later. The storm eventually grew stronger over central Oklahoma than it had been when it was over the Gulf of Mexico. The storm blew through Oklahoma with wind gusts of more than 80 mph and even started to develop an eye-like feature as it approached Oklahoma City.

5. WEIRDNESS: BALL LIGHTNING. CAUSE: UNKNOWN

A healthy fear of lightning is normal. This awe-inspiring phenomenon is hotter than the surface of the Sun and packs enough electrical charge to stop your heart if you're unlucky enough to get struck. Lightning is the subject of extensive scientific study, but we still don't know everything about this immense force of nature, including why it can sometimes form into a ball.

We don't know much about ball lightning outside of the thousands of anecdotal reports from people who were startled by this unusual and short-lived phenomenon. Ball lightning is reportedly lightning that forms into a ball immediately after the strike of a normal bolt of lightning. After forming, it can reportedly move erratically, skip across the ground, and burn through surfaces it touches. Most reports state that it only lasts a couple of seconds before disappearing. A group of Chinese scientists captured this phenomenon on camera for the first time back in 2012, but experiencing it was the result of pure luck—something that doesn't foster much scientific research.

Why Does Humidity Make Us Feel Hotter?

Tomwang112/iStock via Getty Images
Tomwang112/iStock via Getty Images

With temperatures spiking around the country, we thought it might be a good time to answer some questions about the heat index—and why humidity makes us feel hotter.

Why does humidity make us feel hotter?

To answer that question, we need to talk about getting sweaty.

As you probably remember from your high school biology class, one of the ways our bodies cool themselves is by sweating. The sweat then evaporates from our skin, and it carries heat away from the body as it leaves.

Humidity throws a wrench in that system of evaporative cooling, though. As relative humidity increases, the evaporation of sweat from our skin slows down. Instead, the sweat just drips off of us, which leaves us with all of the stinkiness and none of the cooling effect. Thus, when the humidity spikes, our bodies effectively lose a key tool that could normally be used to cool us down.

What's relative about relative humidity?

We all know that humidity refers to the amount of water contained in the air. However, as the air’s temperature changes, so does the amount of water the air can hold. (Air can hold more water vapor as the temperature heats up.) Relative humidity compares the actual humidity to the maximum amount of water vapor the air can hold at any given temperature.

Whose idea was the heat index?

While the notion of humidity making days feel warmer is painfully apparent to anyone who has ever been outside on a soupy day, our current system owes a big debt to Robert G. Steadman, an academic textile researcher. In a 1979 research paper called, “An Assessment of Sultriness, Parts I and II,” Steadman laid out the basic factors that would affect how hot a person felt under a given set of conditions, and meteorologists soon used his work to derive a simplified formula for calculating heat index.

The formula is long and cumbersome, but luckily it can be transformed into easy-to-read charts. Today your local meteorologist just needs to know the air temperature and the relative humidity, and the chart will tell him or her the rest.

Is the heat index calculation the same for everyone?

Not quite, but it’s close. Steadman’s original research was founded on the idea of a “typical” person who was outdoors under a very precise set of conditions. Specifically, Steadman’s everyman was 5’7” tall, weighed 147 pounds, wore long pants and a short-sleeved shirt, and was walking at just over three miles per hour into a slight breeze in the shade. Any deviations from these conditions will affect how the heat/humidity combo feels to a certain person.

What difference does being in the shade make?

Quite a big one. All of the National Weather Service’s charts for calculating the heat index make the reasonable assumption that folks will look for shade when it’s oppressively hot and muggy out. Direct sunlight can add up to 15 degrees to the calculated heat index.

How does wind affect how dangerous the heat is?

Normally, when we think of wind on a hot day, we think of a nice, cooling breeze. That’s the normal state of affairs, but when the weather is really, really hot—think high-90s hot—a dry wind actually heats us up. When it’s that hot out, wind actually draws sweat away from our bodies before it can evaporate to help cool us down. Thanks to this effect, what might have been a cool breeze acts more like a convection oven.

When should I start worrying about high heat index readings?

The National Weather Service has a handy four-tiered system to tell you how dire the heat situation is. At the most severe level, when the heat index is over 130, that's classified as "Extreme Danger" and the risk of heat stroke is highly likely with continued exposure. Things get less scary as you move down the ladder, but even on "Danger" days, when the heat index ranges from 105 to 130, you probably don’t want to be outside. According to the service, that’s when prolonged exposure and/or physical activity make sunstroke, heat cramps, and heat exhaustion likely, while heat stroke is possible.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

This article has been updated for 2019.

Is the Heat Index Real?

MarianVejcik/iStock via Getty Images
MarianVejcik/iStock via Getty Images

Complaining about the humidity is a mainstay of small talk. “It’s not the heat that gets you, it’s the humidity” is a common refrain around the South, just as “it’s a dry heat” is a go-to line in the desert Southwest. The clichés aren’t wrong on this one—a hot and humid day can have a dramatic effect on both your comfort and your health. We can measure this very real impact on your body using the heat index. 

The heat index is the temperature it feels like to your body when you factor in both the actual air temperature and the amount of moisture in the air. If the heat index is 103°F, that means that the combination of heat and humidity has a similar physical impact on your body as it would if the actual air temperature were 103°F. Even though it’s tempting to think of the heat index as an exaggerated temperature that only exists to make the heat sound worse than it really is, scientists came up with the measurements after decades of medical and meteorological research devoted to studying the impact of heat and humidity on the human body. It’s the real deal.

The dew point is an important component of the heat index. The dew point is the temperature at which the air would reach 100 percent relative humidity, or become fully saturated with moisture like on a foggy morning. Since cooler air can’t hold as much moisture as warmer air, lower dew points reflect lower moisture levels and higher dew points indicate higher moisture levels. Dew points below 60°F are comfortable, while readings reaching 70°F and even 80°F range from muggy to downright oppressive.

Measuring humidity on a hot day is important because moisture is how your body naturally cools itself off. Your sweat cools the surface of your skin through a process known as evaporative cooling. If the air is packed with moisture, it takes longer for your sweat to evaporate than it would in more normal conditions, preventing you from cooling off efficiently. The inability to lower your body temperature when it’s hot can quickly lead to medical emergencies like heat exhaustion or heat stroke, which is why the heat index is such an important measurement to pay attention to during the summer months.

The heat index is generally considered “dangerous” once the value climbs above 105°F, and your risk of falling ill increases the higher the heat index climbs.

Dry climates can have the opposite effect on your body, with the distinct lack of moisture in the air making it feel cooler to your body than it really is. Summers get oppressively hot in places like Arizona and Iraq, but the heat doesn’t affect residents as severely because the air is extremely dry. Dew points in desert regions can hover at or below 32°F even when the air temperature is well above 100°F, which is about as dry as it can get in the natural world.  

In 2016, a city in Kuwait measured the all-time highest confirmed temperature ever recorded in the eastern hemisphere, where temperatures climbed to a sweltering 129°F during the day on July 21, 2016. The dew point there at the same time was nearly 100 degrees cooler, leading to a heat index of just 110°F, much lower than the actual air temperature. That’s not necessarily a good thing. Extreme heat combined with extreme aridity can make your sweat evaporate too efficiently, quickly dehydrating you and potentially leading to medical emergencies similar to those you would experience in a much more humid region of the world. 

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

This story has been updated for 2019.

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