A grazier in Queensland's southern inland has captured on camera the moment a "rain bomb" drops from the sky.

Peter Thompson witnessed the weather event at his property just outside of Roma on Sunday afternoon.

He said it was like a "water ball falling".

"I was just out on the tractor on a high point watching the rain come and wondering when I saw it," he said.

"I just saw this and thought 'gee, that looks different', and grabbed my iPhone and started taking photos of it and watched it hit the ground and rolling out," Mr Thompson said.

"I reckon from when I first started seeing that ball form to when it hit the ground was about two minutes.

"The drop itself was really quite quickly. It looked like the bottom of the cloud falling."



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The Bureau of Meteorology said Mr Thompson's rain bomb was in fact a sort of downburst known as a microburst.

"A downburst is a concentrated downdraft, typically lasting five to 15 minutes, and is of unusually high speed such that it can cause damage on, or near, the ground," the BoM website said.

"The term microburst is used to describe a downburst which causes damage over an area with horizontal dimensions of less than four kilometres."

The BoM said a microburst could be characterised as wet or dry.

"A wet microburst, which can occur with a range of thunderstorm types, is accompanied by significant precipitation at the surface," it said.

"It develops in environments characterised by weak vertical wind shear and deep moisture capped by a dry layer.

"In a dry microburst, precipitation at the surface is either very light or does not occur at all, although virga [precipitation falling from a cloud but evaporating before reaching the ground] may be present."