Table of Contents
USA IS FREEZING
- A record-breaking cold wave has swept through the US Midwest, with 22 states hitting sub-zero temperatures.
- Among cities, Chicago dropped to a low of -30°C
- Minneapolis recorded -32°C.
- At least 18 people have died as a result of the cold and snow.
TRUMP
SO WHY SO COLD IN THE USA?
- The extreme cold has been caused by a blast of Arctic air, which in turn is a result of what is known as a “polar vortex” event.
VORTEX MEANING
- NOTES
- First off, the polar vortex describes a large area of upper level (NOT surface) low pressure surrounding the North (and South) Pole, that houses some of the coldest air in the Northern Hemisphere.
- A strong jet stream circulates the high latitudes (called the polar jet stream), and keeps this arctic air bottled up.
SIMPLE EXPLANATION
- Jet Stream – Jet Stream is a upper atmospheric circulation created by the thermal variation between surface and upper atmosphere and equator and poles. It basically flows at a height of 7 to 10kms from the surface of earth(or 9 to 12 above sea level) from west to east in a meander path
JET STREAMS
TYPES OF JET STREAMS
EXPLANATION
- Think of the polar jet stream as a “gate” that confines this cold air well to the north. If this “gate” weakens, the cold air can escape into our region. Certain atmospheric events, can lead to this weakening and “break down” of the polar vortex.
- Sudden stratospheric warming events, strong high pressure ridging, intense Pacific typhoons, and blocking, call all lead to the vortex’s expansion and subsequent squeezing into lobes. These can shift further south and cause arctic outbreaks at the surface in Canada, the United States, Europe, and Russia.
WHAT ROLE DOES CLIMATE CHANGE PLAY?
- There is much debate within the world of meteorology about whether or not this breakdown of the polar vortex is becoming more common.
- Some studies suggest that it is, and some researchers say they suspect that this is down to climate change.
- Jennifer Francis is a senior scientist at the Woods Hole Research Centre, which studies climate change impacts and solutions.
- She argues that melting sea ice in the Arctic may be linked to changes in the polar vortex.
DOESN’T GLOBAL WARMING MEAN EVERYWHERE SHOULD BE WARM?
- A localized, albeit large, cold snap isn’t representative of the rest of the planet, as Australians currently sweltering in searing record heat of more than 46C (114F) will be well aware of.
- The past four years have been the hottest on record for the globe.
HEATWAVES
- According to a study by the Indian Institute of Technology (IIT) Gandhinagar, the frequency of severe heat waves in India will increase 30-fold by 2100 under a 2°C warming scenario.
WILL INDIA ALSO GET SUBJECTED TO COLD BLASTS IF POLAR VORTEX WEAKENS?
- Slipping of polar vortex and the associated spread of cold arctic air is mostly restricted to high-latitude areas (countries like the US or continent like Europe) with some effect on midlatitude regions.
- Most of the Indian subcontinent being low-latitude region don’t expect any impact of shifting vortex in India
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