Lecture

Aerosol-Cloud Interactions: Insights from the East Mediterranean

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Description

This lecture provides an overview of aerosol-cloud interactions in warm and mixed-phase orographic clouds, focusing on studies conducted at Mt. Helmos in Greece. The instructor discusses the Cloud-Aerosol Interaction Studies in the Helmos background Troposphere (CALISHTO) project, which spanned from Fall 2001 to Winter 2022. The lecture highlights the use of in-situ measurements, remote sensing, and modeling to understand the sources of cloud condensation nuclei (CCN) and ice nuclei (IN) in the region. The instructor explains how boundary layer turbulence, vertical aerosol distributions, and meteorological conditions influence cloud microphysical states, including supersaturation and droplet/ice formation. The role of secondary ice processes in mixed-phase clouds is also examined, emphasizing their significance for precipitation formation. The lecture concludes with insights on how the integration of various observational techniques can enhance understanding of these complex atmospheric processes, which are crucial for improving climate models and predicting human impacts on climate.

Official source

Ontological neighbourhood

Earth science

Atmospheric science: Meteorology

Related concepts (32)

Cloud condensation nuclei

Cloud condensation nuclei (CCNs), also known as cloud seeds, are small particles typically 0.2 μm, or one hundredth the size of a cloud droplet. CCNs are a unique subset of aerosols in the atmosphere on which water vapour condenses. This can affect the radiative properties of clouds and the overall atmosphere. Water requires a non-gaseous surface to make the transition from a vapour to a liquid; this process is called condensation. In the atmosphere of Earth, this surface presents itself as tiny solid or liquid particles called CCNs.

Climate

Climate is the long-term weather pattern in a region, typically averaged over 30 years. More rigorously, it is the mean and variability of meteorological variables over a time spanning from months to millions of years. Some of the meteorological variables that are commonly measured are temperature, humidity, atmospheric pressure, wind, and precipitation. In a broader sense, climate is the state of the components of the climate system, including the atmosphere, hydrosphere, cryosphere, lithosphere and biosphere and the interactions between them.

Ice

Ice is water frozen into a solid state, typically forming at or below temperatures of 32 °F, 0 °C, or 273.15 K. Depending on the presence of impurities such as particles of soil or bubbles of air, it can appear transparent or a more or less opaque bluish-white color. In the Solar System, ice is abundant and occurs naturally from as close to the Sun as Mercury to as far away as the Oort cloud objects. Beyond the Solar System, it occurs as interstellar ice.

Cloud physics

Cloud physics is the study of the physical processes that lead to the formation, growth and precipitation of atmospheric clouds. These aerosols are found in the troposphere, stratosphere, and mesosphere, which collectively make up the greatest part of the homosphere. Clouds consist of microscopic droplets of liquid water (warm clouds), tiny crystals of ice (cold clouds), or both (mixed phase clouds), along with microscopic particles of dust, smoke, or other matter, known as condensation nuclei.

Cloud albedo

Cloud albedo is a measure of the albedo or reflectivity of a cloud. Clouds regulate the amount of solar radiation absorbed by a planet and its solar surface irradiance. Generally, increased cloud cover correlates to a higher albedo and a lower absorption of solar energy. Cloud albedo strongly influences the Earth's energy budget, accounting for approximately half of Earth's albedo. Cloud albedo depends on the total mass of water, the size and shape of the droplets or particles and their distribution in space.

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