Algot Runeman wrote:irrotational
(Especially of fluid motion) not rotational; having no rotation.
Residents of Oklahoma and its neighboring states pray for irrotational storms this time of year. Way too often their prayers are not answered. Tornado alley routinely suffers.
With global warming increasing the probability of tornadoes, praying for irrotational storms may seem somewhat irrational, if you'll pardon me for being a man of little faith.