Ballerina skirt is a full skirt that reaches to mid-calf or just above the ankles, often made up of multiple layers of fabric.1 It was a popular style during the 1950s. It is based on the romantic tutu length.
Ballerina skirts have been a consistently popular length for formal dresses, especially for young women.
Geophysics and magnetism
In geophysics, the term is used to refer to a wavy almost-circular region produced by perturbing the equatorial current sheet in a magnetic field whose shape resembles a tutu sticking out from a ballerina's waist.23
^Valerie Cumming, C. W. Cunnington, P. E. Cunnington, The Dictionary of Fashion History, Berg, 2010, p 11
^Markus J. Aschwanden, Physics of the Solar Corona: An Introduction With Problems And Solutions, Springer, 2006, p732
^Wallace Hall Campbell, Introduction to Geomagnetic Fields, Cambridge University Press, 2003, p131