What Is a Tsunami Cloud?
The term “tsunami cloud” has been circulating on social media and in popular conversations, often attached to dramatic photos of strange, rolling cloud formations over the ocean or coastlines. But what exactly is a tsunami cloud, and is it a real meteorological phenomenon?
Understanding the Term
“Tsunami cloud” is not a scientific term. In reality, there are no clouds that are caused by, or indicative of, an actual tsunami. A tsunami is a series of large ocean waves usually caused by an underwater earthquake, landslide, or volcanic eruption. These waves are not connected to cloud formation in the atmosphere.
Instead, the phrase “tsunami cloud” is often used informally to describe certain impressive cloud types that appear to “roll” or “surge” over the horizon in a way that might remind people of a giant wave—a tsunami.
What Are People Actually Seeing?
The clouds most commonly mistaken for “tsunami clouds” are:
1. Shelf Clouds
Description: These are low, horizontal, wedge-shaped clouds associated with thunderstorms. They form along the leading edge of thunderstorm outflow.
Appearance: Shelf clouds look like a giant, rolling wall or wave of cloud advancing toward you. This dramatic appearance often leads to the “tsunami cloud” nickname.
2. Arcus Clouds
Description: This is a broader category that includes shelf clouds and roll clouds.
Appearance: Arcus clouds can look like long, tube-shaped formations or like an advancing wave.
3. Roll Clouds
Description: A rare type of arcus cloud that appears as a horizontal tube-shaped cloud moving slowly across the sky.
Appearance: Unlike shelf clouds, roll clouds are not attached to any other cloud structure and appear to roll on a horizontal axis.
Are Tsunami Clouds Dangerous?
The clouds sometimes called “tsunami clouds” are not dangerous by themselves, but they may signal the approach of severe weather:
Shelf Clouds: Usually mean a thunderstorm is coming, which could bring strong winds, heavy rain, and sometimes hail.
Roll Clouds: Generally not associated with severe storms, but can indicate changes in wind patterns.
Importantly, these clouds do not indicate a real tsunami.
They could, however, indicate an incoming mothership, ala Independence Day…