A spectacular mackerel sky has been captured over Merseyside as the region basks in warm temperatures.

The incredible snap was taken on Wednesday morning in Orrell Park.

Dubbed a 'mackerel sky' due to its appearance like the scaly skin of a fish, the weather phenomenon is caused by high altitude atmospheric waves.

READ MORE:When will the heatwave end? Exact date thunderstorms will hit UK

Known by the Met Office as cirrocumulus clouds, they are made up of lots of small white clouds called cloudlets, which are usually grouped together at high levels.

Composed almost entirely from ice crystals, the little cloudlets are regularly spaced, often arranged as ripples in the sky.

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The Met Office said: "Cirrocumulus cloudlets are usually made up of both ice and 'supercooled' water.

"This means that the water remains a liquid, even at temperatures well below 0C.

"They form when turbulent vertical currents meet a cirrus layer, creating the puffy cumulus shape.

"Cirrocumulus clouds can also form through contrails, the vapour trails left by planes as they fly through a dry upper troposphere.

"These streaks can spread out and become cirrus, cirrostratus and cirrocumulus."

While the clouds are usually associated with fair weather, their appearance can often come before stormy weather.

The Met Office has issued a yellow weather warning for much of the UK for thunderstorms in place from 6pm on Wednesday lasting throughout Thursday until midnight.