Rare phenomenon: Frozen bubbles in Canadian lake

Winter can produce some astonishing works of art, such as these frozen methane bubbles that from beneath the surface of Abraham Lake, Canada.

An extraordinary natural phenomenon attracts several tourists and photographers to Abraham Lake in Canada through the wintertime.

The reservoir on the eastern edge of the Rocky Mountains, in the province of Alberta, is known for its frozen bubbles, most commonly seen from mid-January to early February.

In the clear, dark ice, white bubbles form and in the right light and weather conditions, offer a fascinating sight. Parts of Abraham Lake are already frozen, though temperatures have been well below zero for weeks here.

In the past few days, temperatures have plummeted below -30C. However, given it is still early winter, the 30km long lake has not yet entirely frozen over, which is why later in the season offers optimum conditions.

The bubbles trapped in the ice are not air, but methane. Bacteria from vegetation decaying at the bottom of the lake are responsible for this, as they emit methane when they decompose, creating bubbles in the water.

When the temperature drops through winter, the bubbles then become trapped in the ice, suspended just below the surface of the water.

The methane bubbles then rise to the surface, where they form larger bubbles and freeze in the freezing lake. As the lake continues to freeze, vertical stacks of ice bubbles form, frozen in time. Lake Baikal in Siberia is also known for producing these natural creations.