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Menopausal Mother Nature

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Bumpy flight? Here’s how clouds affect air travel

Bumpy flight: Towering, billowing cumulus reaching plane wing with thin whitte streaks above in blue sky.
Towering cumulus clouds billow under the plane’s wing, while thin cirrus clouds and jet contrails crisscross the sky above, on March 5, 2020. Cumulonimbus clouds in particular can produce a bumpy flight. Image via Lucy Whitt.

Bumpy flight: Clouds and air travel

Sure, there’s clear-air turbulence. But when your airplane ride gets bumpy, you’re likely to look out your window and see clouds. They might range from puffy cumulus clouds, aka fair-weather clouds, to monstrous cumulonimbus with their characteristic anvil-shaped tops, billowing sides and ominously dark bases. The fact is … clouds are cooler than the surrounding air. So it’s the contrast in density between clouds and the surrounding air that creates a sort of “pothole” in the sky, making for a less smooth ride.

Weather and aircraft performance

Mike Sueflohn has been a private and commercial pilot for more than 23 years. As a pilot, he must take part in recurrent training, where they discuss how weather relates to aircraft performance. Some of the issues they focus on are takeoffs, landings and concerns such as wind shear. Sueflohn told EarthSky:

Much of the weather, including turbulence, that we have when flying is derived by the sun and uneven heating of Earth’s surface. As a result, you can experience turbulence at any time. Normally, early in the morning and later in the evening and throughout the night you may find the best time for smooth rides.

Most commercial airlines fly above much of the clouds, though they do still have to fly through them to get in and out of the airports. A typical commercial jet has a cruising altitude of around six to seven miles (nine to 11 km) above sea level. So on a long-distance flight, the plane will generally be above most clouds except for cirrus and the towering cumulonimbus.

Diagram: different types of clouds with height and measurements on sides.
Most commercial jets fly high up in the cirrus level of clouds. Image via Encyclopedia Britannica.

Cumulonimbus: Nature’s detour sign for planes can cause a bumpy flight

As you might guess, storm clouds – specifically cumulonimbus – are the types of clouds that pilots most want to avoid. Cumulonimbus clouds generally contain heavy rain, lightning, hail, strong winds and occasionally tornadoes. Pilots and air traffic control pay close attention to the weather and route flights around these types of storms. As Sueflohn said:

We respect and pay attention to the frontal boundaries where the potential for storm activity/energy exists. Clouds commonly associated with these boundaries that we concern ourselves with are cumulonimbus. Good decision making would be to consider alternate flight planning options where these conditions exist.

Mammatus clouds

Another type of cloud associated with cumulonimbus is mammatus. Mammatus are bubbling pouches of air that hang below the base of a cloud. The website TheAirlinePilots said:

Airline pilots will normally take action to avoid any cumulonimbus clouds, but particularly those bearing mammatus formations, as these indicate especially severe turbulence within the cumulonimbus. Mammatus may be observed wherever cumulonimbus clouds occur, but it is particularly common in areas where thunderstorms are severe, such as tropical and subtropical areas. Because the formation is associated with mature cumulonimbus clouds, it is most likely to be seen from mid-afternoon to early evening, when ground heating and associated convective activity have reached a maximum.

Learn more about why pilots avoid cumulonimbus clouds in the video below.

Other types of clouds

All clouds are made of water droplets or ice crystals. Clouds come in a wide variety of types, from thin to thick and puffy and ranging from low to the ground to the top of the troposphere (and sometimes in the stratosphere. There’s even one type of cloud, called noctilucent clouds, that exist in the mesosphere). Air traffic control specialist Jeffrey Hormann told EarthSky how some of the different types of clouds can affect airplanes:

Cumulonimbus present the most hazards due to the turbulence along with all of the standard thunderstorm fare. Cumulus themselves represent a likelihood of turbulence in the updrafts below them, but smooth air above. Stratus often contain rime ice, especially at their tops, during the colder seasons. Fog and lower visibility restricts aircraft to flying instrument approaches into airports, which below minimum conditions (1/2 mile visibility and 200-foot cloud bases are common) the aircraft cannot continue to land.

Bright white bubbling cloud with large thinner cloud flat top above it.
View at EarthSky Community Photos. | Adelina Bathorja in Tirane, Albania, took this image of an anvil-top cumulonimbus on June 21, 2019. Thank you, Adelina! View Adelina’s photos for a fantastic look at mammatus clouds.

Read more about some unusual cloud types:

Hole punch clouds are made by jets

Undulatus clouds look like wavy rows

Kelvin-Helmholtz clouds look like ocean waves

Cloud gallery from airplanes

Plane wing at top corner and snow-capped mountain with some puffy clouds and darker haze.
This view from an airplane taking off from Portland, Oregon, shows some cumulus clouds around Mt. Hood plus a grayish haze from wildfire smoke on July 21, 2021. Image via Kelly Kizer Whitt.
Airplane wing above layer of small-appearing clouds and blue sky over distant horizon.
Puffy altocumulus clouds in a broken blanket lie beneath this passenger airliner flying at cruising altitude somewhere over Georgia on February 27, 2022. Image via Kelly Kizer Whitt.
White sheet above plane and white sheet below with thin blue line on horizon.
A passenger airplane flies between two layers of stratus clouds on September 24, 2018. Image via Kelly Kizer Whitt.

Bottom line: Many types of clouds and even clear skies can produce a bumpy flight on an aircraft. But cumulonimbus are the most important clouds for airplanes to avoid.


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