One of the most impressive sights in nature is a huge thunderstorm bubbling up on the horizon, smacking the top of the atmosphere and spreading out like a giant umbrella.
The last of them was photographed engulfing the sky of Bangkok, Thailand on November 1, 2016. And here’s a look at how these anvils form.
Thunderstorms are responsible for some of the most incredible images nature can produce, and there are dozens of different types of clouds that come with these beastly bursts of muggy air. Regular cumulus and cumulonimbus clouds are beautiful on their own, but there are different formations and appendages that can make these clouds even more spectacular.
Anvils can dominate the sky and warn of impending danger just as easily as they can act like a textured canvas on which the sunset paints its beautiful oranges and red. These clouds are called “anvils” because of their uncanny resemblance to the anvils blacksmiths use to shape metal.
These impressive cloud formations are a natural result of convection. The development of a thunderstorm is pretty basic. Air near the surface warms unevenly, and some pockets of air wind up warmer (and less dense) than their surroundings, allowing them to freely rise through the atmosphere like a balloon.
Once this pocket of rising air cools to the temperature of its environment (or colder), it stops rising and begins to sink. These columns of rising air—called updrafts—can be pretty strong, rising into the atmosphere at more than 100 MPH in the most intense thunderstorms.
The vast majority of thunderstorms aren’t strong enough to reach the top of the atmosphere, but when they do, the results are phenomenal. The point of the atmosphere at which a rising pocket of air stops rising is known as the “equilibrium level.”
When updrafts hit the equilibrium level, one of two things can happen—the air spreads out as if it hit a ceiling, or if the updraft is powerful enough, the air breaks through the layer and creates what’s known as an “overshooting top.” Storms with overshooting tops are usually severe, as updrafts this much oomph can support the weight of some ugly hailstones at the least.
Once the updrafts hit the equilibrium level, the air fans out in all directions, allowing a thick ceiling of cirrus clouds to extend out and away from the hulking cumulonimbus cloud. Here a timelapse video of this giant cloud over Bangkok, Thailand on Nov. 1st:
The pictures above and below could become some of the most widely-circulated thunderstorm pictures on the internet. They are classic examples of an anvil and its associated overshooting top, with a great view of the parent thunderstorm below. And here some other pictures of this impressive storm cell with music:
Widespread anvils with large pockets of overshooting tops are indicative of severe weather. So if you see one of these monstrous formations crawling towards you one day, get ready to find sturdy shelter once it arrives.