Atmosphere / solar radiation

Atmosphere / solar radiation

Arctic Marine Cloud Brightening

Roughly one-third of the incoming solar radiation is directly reflected back into space by the Earth’s atmosphere and surface albedo. Clouds play an important role in this, although their role is double as water droplets can also interfere with outgoing longwave radiation, thereby contributing to the greenhouse effect. Over open water clouds can make a particularly big difference as the albedo of the water is below 0.1, thereby absorbing most of the sun’s energy.

Clouds over Setesdalsheia, Norway, October 2013

Atmosphere / solar radiation

Cirrus cloud thinning

Cirrus clouds are high altitude ice clouds. They influence the Earth’s radiation budget as they reflect both incoming and outgoing radiation. However, they ultimately have a warming effect as they are more efficient at trapping outgoing longwave radiation (Kärcher 2017).

Mountain pine and spruce forest in winter, Hillestadheia, Norway

Atmosphere / solar radiation

Snowfall enhancement

With the exception of some regions like Antarctica, global snowfall amount and frequency have decreased, and the timespan during which snow cover remains has shortened (Zender 2012). This has multiple effects on human and natural systems as it influences widely diverging processes such as reducing surface albedo and changes in the hydrological cycle.

Atmosphere / solar radiation

Space-based solar radiation management

One of the most intuitive SRM approaches would be to reflect or block some solar energy before it reaches the Earth’s atmosphere.

Clouds over peaks in Uummannaq, Greenland

Atmosphere / solar radiation

Arctic winter high-latitude seasonal stratospheric aerosol injection

Stratospheric aerosol injection (SAI) is an idea to inject particles in the stratosphere to reduce the amount of incoming solar energy (Rasch et al. 2008; Irvine et al. 2016).

Atmosphere / solar radiation

Mixed phase regime cloud thinning over the polar oceans during winter

Clouds play an important role in the Earth’s energy system. The effects of clouds are complex and diverse, often having simultaneous cooling and warming effects. Mixed-phase clouds (MPC) are clouds that contain water vapor, ice particles, and supercooled water droplets. MPCs are still poorly understood and 'notoriously difficult to represent in numerical weather prediction and climate models' (Korolev et al. 2017).