Researchers measured the coldest temperature ever recorded by a satellite of a cloud captured by the Visible Infrared Imaging Radiometer Suite (VIIRS) onboard the NOAA-20 weather satellite. VIIRS is a sensor capable of measuring temperature of the Earth and its atmosphere.
A recently published research letter in Geophysical Research Letters discusses the finding by researchers Simon Richard Proud of the National Centre for Earth Observation in Oxford, England, and Scott Bachmeier of the Cooperative Institute for Meteorological Satellite Studies at the University of Wisconsin at Madison.
Analysis of 16 years of satellite temperature data
The researchers analyzed more than 16 years of satellite-derived temperature data collected between August 2004 and August 2020.
What stood out in their inventory was one particularly cold measurement captured around 13:38 UTC on December 29, 2018 by the the VIIRS onboard the NOAA‐20 weather satellite. One pixel located in the Western Pacific in the data collected at that time registered a temperature of 161.96K (-111 degrees Celsius, -168 degrees Fahrenheit).
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Previous studies have shown a temperature of 170.9K that was detected in Tropical Cyclone Hilda in 1992 and a VIIRS temperature recording of 163.75K while overflying Typhoon Kammuri in 2019. This makes the reading of 161.96K is the lowest known measurement recording by a satellite of a cloud.
Calibration challenges of VIIRS at low temperatures
The researchers do note in their paper that while temperatures as low as -173 degrees Celsius can be measured (-279 Fahrenheit, 100K) by VIIRS, the sensor is “not very well calibrated for measuring such low temperatures”.
Why are These Clouds so Cold?
The clouds that form thunderstorms, tropical cyclones, and other forms of extreme convective weather are usually at high altitude and therefore experience temperatures that are well below zero.
The ice clouds that form when a thunderstorm updraft ascends and then flattens out at the tropopause are known as anvils. Temperatures in the tropopause average about-60°F (-51°C). Particularly severe storms create overshoots that can reach into the stratosphere and are cooler than the anvil.
The importance of studying cloud temperature
Ultra cold clouds are a sign of impending severe weather. Colder cloud tops can drive high winds, heavy rain, hail, lightning, and tornadoes.
Tracking cold temperature clouds using satellite data, helps atmospheric scientists forecast extreme weather potential. The information may be useful as scientists track and learn how storm systems can become more powerful as a result of climate change.
“Measuring a cloud’s coldest temperature is a good way to gauge the height of cloud tops, which helps to estimate the stage of storm development or its potential to produce severe weather,” says Bachmeier.
The Study:
Proud, S. R., & Bachmeier, S. (2021). Record‐Low Cloud Temperatures Associated With a Tropical Deep Convective Event. Geophysical Research Letters, 48(6), e2020GL092261. https://doi.org/10.1029/2020GL092261
Verbeten, R. (2021, May 14). Coldest cloud temps recorded by weather satellite. Space Science and Engineering Center. https://www.ssec.wisc.edu/news/articles/13654/
