eddy

https://doi.org/10.1351/goldbook.E01888
In turbulent fluid motion, a blob of the fluid that has some definitive character and moves in some way differently from the main flow.
Source:
PAC, 1990, 62, 2167. 'Glossary of atmospheric chemistry terms (Recommendations 1990)' on page 2186 (https://doi.org/10.1351/pac199062112167)