Evidence that small (typically less than 1 μm in size) particles known as aerosols are a source of heat in Jupiter’s atmosphere is put forward in Nature Communications this week. Aggregates of these particles are suggested to exert a large influence on the amount of solar radiation absorbed by Jupiter’s atmosphere and can account for a missing heat source in previous models.
In Earth’s atmosphere, aerosols play an important role - affecting the amount of solar radiation transferred to and from the Earth’s surface and influencing climate - but their influence on the climate of giant planets has been unclear up to now.
Using observations from NASA’s Voyager and Cassini spacecrafts, Xi Zhang and colleagues show that gases alone cannot maintain the balance between incoming and outgoing energy in the middle part of Jupiter’s atmosphere and suggest that aerosols play a dominant role. They propose that a thick aerosol layer dominates the heating in this part of the atmosphere by interacting with incoming radiation. The authors suggest that hydrocarbon compounds come together and condense as aerosol particles, or haze particles, absorbing heat from the sun in the mid to high latitudes and heating Jupiter's atmosphere, and that they may also affect atmospheric cooling by reflecting sunlight. Based on these results, the authors suggest that Jupiter’s atmosphere has a different energy regime to that of Earth.
Although the current study focuses on Jupiter, it may help to shed light on the atmospheres of other planets in the Solar System - such as Saturn, Uranus and Neptune - as well as extra-solar planets. The authors suggest that aggregates of aerosols may affect the climate evolution and distribution of energy from the Sun in other giant planets, and may also have been important in the atmosphere of the early Earth.