Mountainous air drives tiny biological particles in ice layers in the clouds

A team of international researchers reveals a surprising daily rhythm in the air above the mountainous areas that can reshape our understanding of extreme precipitation. The study, published Sunday in the NPJ Journal of Climate and Atmospheric Science, reveals how microbiological particles from forests create a 24-hour cycle that affects cloud formation and may trigger intense stormwater events.

Scientists and collaborative agencies at EPFL (EPFL (École Polytechniquefé dérale de Lausanne) found that the concentration of ice core particles (INPs)—the miniature air materials that help produce ice in the clouds—follow a unique pattern throughout the day. These particles include pollen, bacteria, spores and plant matter, peaking around noon and reaching minimum levels at night.

“Bio particles form ice in clouds very efficiently, and ice formation is most of the precipitation that the earth receives worldwide, as ice falls quickly from the sky,” explained Athanasios nenes of the EPFL atmospheric processes and its impact, and researcher Kunfeng Gao led the study with researcher Kunfeng Gao.

The research team conducted measurements on Mount Helmos, Greece, which rose at an altitude of 2,314 meters. As the temperature rises in the morning, the forest below the mountain releases upwardly floating biological particles, descending in the evening, approaching the evening and reaching its highest levels in the afternoon.

The importance of these findings goes beyond academic interests. Current weather and climate models largely ignore these biological particles and their daily cycles – an important oversight that may affect the accuracy of current and future climate predictions.

The study examined a variety of atmospheric conditions and compared the number of days affected by desert dust and localized biological particles. While both promote ice formation, the researchers found that biological particles have particularly powerful effects during the day and in the absence of dust events.

According to this study, different types of biological particles appear to have different effects. When local forest sources dominate, certain bacteria-sized particles are closely related to ice formation, while larger fungal spores and pollen fragments become increasingly important in dust events.

In contrast, the researchers found that particles containing black carbon (usually from fossil fuel combustion) had little effect on ice formation, although their impact on other cloud processes was known.

Nenes recently participated in the IPCC scope meeting for the organization’s seventh assessment report and is now leading the second campaign known as Chopin at Mount Helmos. This follow-up study deploys extended tools including cloud radar, aerosol laser shooting, drones and bound balloons to further characterize how each type of biological particles affects cloud formation.

“Given our findings, weather and climate models absolutely need to consider bioparticles, especially because as climate warms, it is expected that bioparticles will increase in the atmosphere.”

These findings increase our understanding of mountain precipitation around the globe. When used in conjunction with subsequent processes such as ice reproduction, these biological particles can quickly emit clouds and may generate substantial snowfall and extreme precipitation.

The research team is now working with the European Space Agency and other consortiums to apply its discoveries to satellite data, improving our ability to understand and predict how airborne particles affect cloud and precipitation patterns to the “species post-world.”