Climate change is not going away. This will be a difficult year for some life on earth. Case in point, extreme heat is ‘boiling’ the brains of bats in southern Australia.
More than 200 bats have lost their lives to southern Australia’s ongoing heat wave.
As temperatures rose to 111.5 degrees Fahrenheit (44.2 degrees Celsius) in Campbelltown in the Australian state of New South Wales, a colony of flying fox bats that lives near the town’s train station felt the effects. Volunteers struggled to rescue the heat-stricken bats, according to the Campbelltown-Macarthur Advertiser, but at least 204 individual animals, mostly babies, died.
“They basically boil,” Kate Ryan, the colony manager for the Campbelltown bats, told the newspaper. “It affects their brain — their brain just fries and they become incoherent.” [Watch for Falling Iguanas! Bomb Cyclone Drops Frozen Lizards]
Rescuers with Help Save the Wildlife and Bushlands in Campbelltown posted on their Facebook page details of the dire situation: “As the dead bodies were recovered and placed in a pile for a head count the numbers had reached 200 not including the many hundreds that were still left in trees being unreachable, sadly a few adults were also included in the body count. It was a long and heartbreaking afternoon…”
The colony of flying foxes in Campbelltown belong to the species Pteropus poliocephalus, better known as the gray-headed flying fox. Their wingspans can stretch more than 3.3 feet (1 meter), and they can weigh more than 2.2 lbs. (1 kilogram). Important pollinators, the bats eat mainly nectar, pollen and fruit.
Temperatures higher than 86 degrees F (30 degrees C) can be dangerous to young flying foxes, Ryan told the Advertiser, because their bodies lose the ability to regulate their temperature. For the Campbelltown colony, a lack of both water and shade exacerbates the problem, she said.
Southern Australia’s heat has reached far beyond 86 degrees F in the past several days. Most of New South Wales is experiencing a severe heat wave, according to the Australian Bureau of Meteorology. On Jan. 6, a weather station in the Sydney suburb of Penrith recorded a reading of 116.78 degrees F (47.1 degrees C), the hottest in the Sydney metro area since 1939, when a nearby station recorded a temperature of 118.04 degrees F (47.8 C).
My grandfather had a masters degree in meteorology and after the Airforce, worked for the Atomic Energy Commission. I share his curiosity about mechanisms that cause our weather.
What causes heat waves? Heat waves happen when sustained high pressure from 10K to 25K feet for days to weeks keeps hot air from escaping.
When high pressure from aloft—10,000-25,000ft remains strong over an area for several days to weeks, heat waves occur. This happens both in the Northern and Southern Hemispheres during the summer as the jet stream follows the path of the sun. On the equator side of the jet stream, high pressure builds up in the middle layers of the atmosphere. Because summertime weather patterns tend to be slower than wintertime patterns, the mid-level pressure also moves very slowly. The air sinks towards the surface under high pressure and then acts as a cap holding in the hot air. Because the air cannot lift, cumulus clouds are less likely to form, making rain unlikely. The build up of heat on the surface then becomes a heat wave.
What causes high pressure at high altitudes? A situation called 4-mile-high pattern wave No. 5?
Meteorologists may have found a way to predict some killer heat waves up to three weeks in advance. Now, the best they can do is about 10 days. An earlier warning would help cities prepare for the heat wave, arrange to open up cooling centers and check on the elderly, said Gerald Meehl, co-author of a study that describes the forecasting clue.
“It gives you a little bit of a heads up of what’s coming,” he said.
The key may be a certain pattern of high and low pressure spots across the globe high in the sky. When that pattern shows up, the chances double for a prolonged and intense heat wave in the eastern two-thirds of the United States, according to the study published Sunday in the journal Nature Geoscience. .. They did thousands of computer simulations and discovered that when high pressure and low pressure systems line up in a specific pattern, it foreshadows heat to come in about 15 to 20 days. Scientists call this 4-mile-high pattern wave No. 5.
The research team discerned the pattern by analyzing a 12,000-year simulation of the atmosphere over the Northern Hemisphere. During those times when a distinctive “wavenumber-5” pattern emerged, a major summertime heat wave became more likely to subsequently build over the United States.
“It may be useful to monitor the atmosphere, looking for this pattern, if we find that it precedes heat waves in a predictable way,” says NCAR scientist Haiyan Teng, the lead author. “This gives us a potential source to predict heat waves beyond the typical range of weather forecasts.”
The wavenumber-5 pattern refers to a sequence of alternating high- and low-pressure systems (five of each) that form a ring circling the northern midlatitudes, several miles above the surface. This pattern can lend itself to slow-moving weather features, raising the odds for stagnant conditions often …
What causes wavenumber-5 pattern, the heat wave harbinger?
This pattern is not caused by particular oceanic conditions or heating of Earth’s surface, but instead arises from naturally varying conditions of the atmosphere. It is associated with an atmospheric phenomenon known as a Rossby wave train that encircles the Northern Hemisphere along the jet stream. …
During the 20 days leading up to a heat wave in the model results, the five ridges and five troughs that make up a wavenumber-5 pattern tended to propagate very slowly westward around the globe, moving against the flow of the jet stream itself. Eventually, a high-pressure ridge moved from the North Atlantic into the United States, shutting down rainfall and setting the stage for a heat wave to emerge.
In other words, from looking at the available data, it appears we don’t yet know the causes, but we did find a large pattern of pressures in the atmosphere which predicts a heat wave with some degree of certainty.