In Kansas City and Tulsa, overnight lows have seldom dipped much below 80°F, with consistently oppressive humidity. Pulses of tropical air flowing north and east from the Gulf of Mexico are largely to blame.

One of the most influential and colorful atmospheric scientists of modern times passed from the scene unexpectedly on 19 July. Stephen Schneider died of an apparent heart attack while on board a flight from Sweden to London.

Researchers and aircraft will search for secrets of hurricane formation above the tropical Atlantic Ocean.

The study, published in Nature Geoscience, finds that the rise is at least partly a result of climate change.