Researchers have pinpointed the ‘natural thermostat’ that cools the air in Earth’s upper atmosphere after violent solar storms.
This activity includes solar flares and coronal mass ejections (CMEs) – which release electrically charged plasma from the sun.
It is known to damage satellites, cause power outages back on Earth, and even disrupt GPS navigation services.
Researchers have pinpointed the ‘natural thermostat’ that cools the air in Earth’s upper atmosphere after violent solar storms. This activity includes solar flares and coronal mass ejections or CMEs (illustrated) – which release electrically charged plasma from the sun
CMEs are powerful enough to send billions of tons of solar particles hurtling toward Earth at more than 1 million miles (1.6km) per hour, according to University of Colorado Boulder Professor Delores Knipp.
The researchers found that when such powerful CMEs speed toward Earth, they create shock waves similar to supersonic aircraft creating sonic booms.
While energy from the shock waves expands and heats up Earth’s upper atmosphere, it also causes nitric oxide to form.
This chemical rapidly cools and shrinks the atmosphere.
‘What’s new is that we have determined the circumstances under which the upper atmosphere goes into this almost overcooling mode following significant heating,’ said Professor Knipp.
‘It’s a bit like having a stuck thermostat – it’s really a case of nature reining itself in.’
While CMEs slamming into Earth’s atmosphere can cause temperature spikes of up to 750 degrees Fahrenheit (399 degrees Celcius), the nitric oxide can cool it by around 930 degrees Fahrenheit (499 degrees Celcius), said Professor Knipp.
The findings came about when Professor Knipp was reviewing satellite data from a severe solar storm in 1967.
‘I found a graphic buried deep in a long forgotten manuscript,’ she said.
‘It finally suggested to me what was really happening.’
As coronal mass ejections or CMEs – which release electrically charged plasma from the sun – cause the upper atmosphere to expand, satellites in low-Earth orbit experience more drag as they are forced to move through extra gaseous particles.
Satellite drag is a major concern for aerospace firms as it causes orbit decays for spacecraft, which eventually burn up in our planet’s atmosphere.
The new study compared two 15-year-long sets of satellite data.
One was from the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument riding on Nasa’s TIMED satellite.
The other was collected by the U.S. Department of Defense satellites.
‘We found that the fastest material streaming off the sun was triggering these shockwaves, causing the atmosphere to heave up and heat up,’ said Professor Knipp.
‘But it became very clear that these shock waves were at the root of creating the nitric oxide, which caused the atmosphere to shed energy and cool.’