This is due to a huge ridge of high pressure, associated with sinking air, trapping the heat being advected from the south.
One industry that continued to thrive was the smuggling through the Roki Tunnel, which cuts through the huge ridge of the Caucasus.
By late morning we had left the Moisie to follow another river, the Nipissis, flowing down from a huge ridge line to our north.
Here's how we look right now: -9: Kaymer (9) -4: de Jonge (11), Na (9) -3: Compton (13), Stenson (11) -2: Fowler (15), Kuchar (11), D Johnson (10), Snedeker (9) -1: Spieth (13) E: Bradley (11), Koepka (9) 10.29pm BST Kaymer finds the middle of the par-three 9th, but he's left with a mammoth putt over a huge ridge.
Their sledges of supplies were pulled by dogs (the British were finally learning from Amundsen), but the boats had to be dragged by the men across the ice and over huge ridges formed by the collision of floes.
The oceanic Aleutians comprise a chain of mountainous volcanic peaks, the crest of a huge submarine ridge some 1,500 miles (2,400 km) long and 20 to 60 miles (32 to 96 km) wide that rises 11,000 feet (3,350 metres) above the seafloor.
So when the huge heat ridge builds over the central U.S. over the weekend, intersecting the northern regions with high soil moisture, humidity levels will go through the roof in places like Minneapolis and Des Moines, even if actual air temperatures are slightly dampened.
Before each trip, Hadow spends hours on Dartmoor pulling strings of tyres around tors, getting caught on and under rocks, untangling, pulling, shoving and scrabbling over cold wet granite to prepare for the huge pressure ridges he will have to clamber over: steep walls of frozen slippery ice rubble which test both his physical strength and patience.
At the beginning of December a huge high-pressure ridge parked off the Pacific coast, creating these perfect conditions for strong Southern California outflow Santa Ana dry winds.
"Ice and meltwater cool the erupting magma and constrain its flow, building huge towers and ridges within the ice," says Dave McGarvie, a volcanologist at The Open University, who is at Bárðarbunga now.
The 30-acre strip of donated land, a wing-shaped wedge of new-growth woods that borders on the giant Ward Pound Ridge Reservation, has huge boulders, craggy ridges and caves where the Whitehead boys, Charlie, now 31, and Sam, now 34, played growing up, and where the family used to take long walks together.
