Polar vortex: U-M researchers explain impacts

The Midwest is in the grip of record-breaking extreme cold this week. University of Michigan engineering researchers can explain the weather phenomenon and what it will likely mean for residents in the affected areas.

Great Lakes effect

When we hear lake effect weather, many think of increased snowfall on the west side of the state caused by Lake Michigan. But Frank Marsik, a meteorologist and associate research scientist in climate and space sciences and engineering, says the Great Lakes can also lead to a change in air temperature thanks to warmer surface water compared to air temperatures.

“Just as heat is lost from a warm body to the cold air surrounding it (think wind chill), considerable heat will be lost from the lakes to the atmosphere as Arctic air moves across the regional over the next several days,” said Marski. “As a result, temperatures across much of Michigan will appear ‘moderate’ compared to those experienced in the western Great Lakes.”

A weather map forecasting expected temperatures on Jan. 30, 2019.

The role of climate change

While this pocket of cold air is sweeping across the country is making headlines, Richard Rood, a professor of climate and space sciences and engineering, says it’s not representative of what’s happening on a global scale.

“While we are worried about a very small little blob of cold air, that blob is surrounded by air that is 15 degrees warmer than average,” he said.

In Alaska and Canada, the warmer-than-usual weather is even more extreme with some days closer to 30 degrees above average. Compared to a long term average, he said, there are many more record highs being set up north, and relatively few new lows being set.

“As the climate warms, wintertime weather systems are more frequently displacing cold polar air from the highest latitudes. This displaced air brings cold temperatures to the lower latitudes. What is telling is that the area of the polar air is decreasing, and it is shorter lived.”

Cold weather’s effect on your commute

Regardless of whether your vehicle is electric or has a gas or diesel engine, travel during times of extreme cold can be challenging.

Traditional diesel and gasoline engines produce a lot of waste heat, which Margaret Wooldridge, a professor of mechanical engineering, says is used to heat passenger compartments of vehicles. Electric vehicles, on the other hand, don’t work that way.

“Electric vehicles do not have comparable levels of waste heat, and have to use supplemental heating systems for the passenger compartments,” Wooldridge said. “This additional use of electric power will lead to faster drain on batteries.”

Just like cell phones, batteries inside electric vehicles don’t perform as well in cold temps, reducing electric vehicles’ range.

Anna Stefanopoulou, a professor of mechanical engineering and director of the U-M Energy Institute, recently published a paper with colleagues exploring best practices for preparing to start a vehicle battery in sub-zero weather.

“At cold temperatures, it is important to have plenty of energy left so you can start.” Stefanopoulou said. “Don’t think that being near an outlet to charge will get you out of trouble. Our recent work shows that at low temperatures, you cannot charge, and it will be faster to discharge to warm up the battery a bit so it can safely accept the charging. So again, you need to leave plenty of charge to be able to start and go!”

Andre Boehman, a professor of mechanical engineering and director of U-M’s W.E. Lay Automotive Laboratory, raises important points about operating diesel vehicles in frigid temperatures.

“Diesel vehicles should be properly winterized. But when temperatures get extremely low, you run the risk of having the fuel form a wax, primarily from the ‘paraffin’ compounds in the fuel. This can clog your fuel filter and restrict flow to the engine, and could lead to wear within the engine over a sufficient number of very cold starts, and is another reason to keep a block heater on your diesel engine.”