This menacing shelf cloud darkened the sky of Rio Grande do Sul, Brazil on April 6, 2016.
The cloud itself is completely harmless, but it’s a sign that you should run for your life before the storm hits!
![shelf cloud brazil rio Grande do sul, shelf cloud brazil pictures, monster shelf cloud brazil april 6 2016, shelf cloud brazil april 6 2016, rio grande do sul shelf clouds pictures](https://strangesounds.org/wp-content/uploads/2016/04/shelf-cloud-brazil-rio-Grande-do-sul-2.jpg)
Shelf clouds are a stunning feature of many spring and summertime thunderstorms that often pack more bark than bite.
![shelf cloud brazil rio Grande do sul, shelf cloud brazil pictures, monster shelf cloud brazil april 6 2016, shelf cloud brazil april 6 2016, rio grande do sul shelf clouds pictures](https://strangesounds.org/wp-content/uploads/2016/04/shelf-cloud-brazil-rio-Grande-do-sul-3.jpg)
Other than for their incredible beauty, shelf clouds are usually newsworthy because they tend to freak people out.
![shelf cloud brazil rio Grande do sul, shelf cloud brazil pictures, monster shelf cloud brazil april 6 2016, shelf cloud brazil april 6 2016, rio grande do sul shelf clouds pictures](https://strangesounds.org/wp-content/uploads/2016/04/shelf-cloud-brazil-rio-Grande-do-sul-4.jpg)
A shelf cloud is a low-hanging, well-defined, wedge-shaped formation that occurs along the leading edge of a gust front in a thunderstorm.
![shelf cloud brazil rio Grande do sul, shelf cloud brazil pictures, monster shelf cloud brazil april 6 2016, shelf cloud brazil april 6 2016, rio grande do sul shelf clouds pictures](https://strangesounds.org/wp-content/uploads/2016/04/shelf-cloud-brazil-rio-Grande-do-sul-5.jpg)
Shelf clouds most often form just ahead of intense lines of thunderstorms.
![shelf cloud brazil rio Grande do sul, shelf cloud brazil pictures, monster shelf cloud brazil april 6 2016, shelf cloud brazil april 6 2016, rio grande do sul shelf clouds pictures](https://strangesounds.org/wp-content/uploads/2016/04/shelf-cloud-brazil-rio-Grande-do-sul-6.jpg)
Even though they look ominous and people often mistake them for tornadoes, shelf clouds themselves are harmless.
![shelf cloud brazil rio Grande do sul, shelf cloud brazil pictures, monster shelf cloud brazil april 6 2016, shelf cloud brazil april 6 2016, rio grande do sul shelf clouds pictures](https://strangesounds.org/wp-content/uploads/2016/04/shelf-cloud-brazil-rio-Grande-do-sul-7.jpg)
What they indicate, however, is potentially more dangerous.
![shelf cloud brazil rio Grande do sul, shelf cloud brazil pictures, monster shelf cloud brazil april 6 2016, shelf cloud brazil april 6 2016, rio grande do sul shelf clouds pictures](https://strangesounds.org/wp-content/uploads/2016/04/shelf-cloud-brazil-rio-Grande-do-sul.jpg)
These clouds most often form along intense lines of thunderstorms.
![shelf cloud brazil rio Grande do sul, shelf cloud brazil pictures, monster shelf cloud brazil april 6 2016, shelf cloud brazil april 6 2016, rio grande do sul shelf clouds pictures](https://strangesounds.org/wp-content/uploads/2016/04/shelf-cloud-brazil-rio-Grande-do-sul-9.jpg)
These storms, called squall lines or bow echoes, tend to produce damaging winds when they hit.
![shelf cloud brazil rio Grande do sul, shelf cloud brazil pictures, monster shelf cloud brazil april 6 2016, shelf cloud brazil april 6 2016, rio grande do sul shelf clouds pictures](https://strangesounds.org/wp-content/uploads/2016/04/shelf-cloud-brazil-rio-Grande-do-sul-1.jpg)
The most well-defined and photogenic shelf clouds occur with the most intense type of severe thunderstorm called a “derecho.”
![shelf cloud brazil rio Grande do sul, shelf cloud brazil pictures, monster shelf cloud brazil april 6 2016, shelf cloud brazil april 6 2016, rio grande do sul shelf clouds pictures](https://strangesounds.org/wp-content/uploads/2016/04/shelf-cloud-brazil-rio-Grande-do-sul-10.jpg)
As spring sets in over the next few months, shelf clouds will become a common sight. The cloud itself is completely harmless, but it’s a sign that you should get inside before the storm hits.
On Good Friday, another monster shelf cloud swept through Florida.