NASA data showed unusually warm air over the northern Pacific and Atlantic Oceans this summer.
Scientists at NASA believe they have an explanation for the "heat dome"
of 2011 that contributed to the persistently hot temperatures
throughout the South and Midwest this summer.
Data from the NASA's satellite-based Atmospheric Infrared Sounder (AIRS) shows that air temperature over the northern subtropical regions of the Pacific and Atlantic Oceans this year was slightly above normal, contributing to greater atmospheric pressure.
And while the pressure anomalies were small,
they could drive changes in the atmospheric circulation sufficient to
break heat records at the surface, according to NASA.
That's especially true when observing the pressure system over the Atlantic (below), which consistently drove
surface winds from the warm and humid tropics into much of the
continental United States