The temperatures measured at the top of the volcanic cloud generated by the eruption of the Indonesian volcano Anak Krakatau, in December 2018, for six days reached -80 °C at an altitude of about 18 km, generating up to ten million tons of ice and triggering about 100.000 lightning strikes
On December 22, 2018, a violent explosive eruption affected the Indonesian volcano Anak Krakatau. The eruption generated enormous quantities of ice and lightning and a tsunami occurred due to the partial collapse of the volcanic edifice into the sea.
The case was the subject of the study Anak Krakatau triggers volcanic freezer in the upper troposphere, conducted by an international team including researchers from the National Institute of Geophysics and Volcanology (INGV) and published in the journal Nature Scientific Reports. Using satellite data, ground observations and an eruptive column model, the height of the volcanic cloud was for the first time related to the frequency of lightning generation.
"For six days", explains Stefano Corradini, INGV researcher, "the storm, fueled by the heat generated by volcanic activity, brought the eruptive column to reach heights of between sixteen and eighteen kilometers with temperatures at the top down to -80°C C".
Volcanic activity that occurs in humid tropical atmospheres can promote heat transfer and trigger volcanic thunderstorms. However, these phenomena rarely last for more than a day.
“The water vapor frozen at high altitudes”, continues Stefano Corradini, “has generated up to ten million tons of ice. This massive amount of ice kept in the upper troposphere for days, together with the rapid updrafts, has caused the generation of a huge number of lightning strikes, up to 72 per minute. Similar events are extremely rare even for weather storms,” concludes the researcher.
