Funnel clouds, twisters, tornados: What are they?

Funnel cloud over Glasgow
Image caption Ally MacPherson said the 'mini tornado' lasted around 20 minutes in Glasgow.
Funnel cloud over Glasgow
Image caption The funnel cloud over Glasgow at 18:00 on Saturday evening. Photograph by David Woods.
Funnel cloud over Dumfries and Galloway
Image caption Cloud was followed by an electrical storm over Balmaclellan, Dumfries and Galloway, said Rebecca Rumble.
Funnel cloud over Tarbolton
Image caption David Frew spotted this funnel cloud just before a thunderstorm in Tarbolton, south west Ayrshire.
Funnel cloud near Ayr
Image caption David Allen saw this 'twister' near Ayr.
Funnel cloud over Glasgow
Image caption 'Three minutes later, it was gone", said Arthur Hansson of the cloud he saw from his flat in Glasgow.

During the stormy weather over the weekend and on Monday, BBC Scotland news website readers have been sending pictures of funnel clouds. But what are they and why are we getting them?

A funnel cloud usually forms during a thunderstorm or heavy shower, from a cumulonimbus cloud or a large cumulus cloud, when the atmosphere is unstable.

It consists of condensed water droplets and is associated with a column of air that rotates as it is drawn into the cloud.

Funnel clouds look like cone-shaped or thin rope-like protuberances which hang down from the cloud base, and often do not last very long.

If a funnel cloud touches the ground it is generally regarded as a tornado and could lift debris and even cause some minor damage on the ground - depending on the strength of convection within the cloud.

If the funnel cloud touches down at sea we get what is known as a waterspout.

The UK regularly sees bouts of unstable, showery weather throughout the year during every season.

Funnel clouds are not an uncommon weather phenomenon right across the country.

People who have observed a funnel cloud passing overhead have described the sound as similar to buzzing bees or a rushing waterfall-like sound.

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