article_snippet.sent: But exactly how this wind movement forms the structures is disputed.
article_snippet.sent: But exactly how this wind movement forms the structures is disputed.
article_snippet.sent: These are long rolls of air that spiral, or rotate one way before rotating another.
article_snippet.sent: These are commonly seen in clouds, creating what's known as 'cloud streets' that appear as cumulus-type clouds.
article_snippet.sent: Observations in the atmosphere and in the laboratory indicate that dominant forms of motion in the boundary layer of the atmosphere are counter-rotating helical roll vortices aligned along the wind. '
article_snippet.sent: These are long rolls of air that spiral, or rotate one way before rotating another.
article_snippet.sent: These are commonly seen in clouds, creating what's known as 'cloud streets' that appear as cumulus-type clouds align to be parallel to the wind (illustrated right)
article_snippet.sent: But measured dimensions of roll vortices indicate their wavelength ranges between less than 50 metres and 31 miles (15 km). '
highlights_snippet.sent: Theories include helical roll vortices - rolls of rotating and spiralling air - and seasonal changes in wind direction .