WELCOME TO THE JOHNSON CLOUD LAB
Studying the atmospheres of Earth, Mars, and beyond one experiment at a time
EARTH BASED CLOUD MICROPHYSICS
We use laboratory based instrumentation and observations to learn about the small scale processes at work in cloud formation and the properties of the resulting cloud particles. Our findings are used to address fundamental questions such as: What aerosols act as cloud condensation nuclei and ice nuclei? What are the ice multiplication processes at work in our atmosphere? How do cloud particles interact with radiation from the sun?
Although not as pronounced as on Earth, clouds are a common feature of the Martian atmosphere. In fact, the temperature and pressure are such that Mars is host to both water ice and carbon dioxide ice clouds. Despite the family of rovers and orbiters that have visited the red planet many questions remain about the formation pathways and conditions, climatological impacts, and interactions between types in both the past and present Martian Atmosphere.
(Image courtesy of NASA/STSci)
Over the past 20+ years the field of exoplanets has boomed, uncovering thousands of planets in only a small portion of our galaxy. Astronomers have begun to study the properties of these planets in amazing detail through satellite and ground based observations. Although exoplanet atmospheres have been detected the presence of clouds, hazes, and aerosols poses major challenges to their characterization. How can we learn about these atmospheres if our view is blocked by these particulates? The answer may lie in laboratory measurements of exoplanet analogs.
TRANSIENT LUNAR ATMOSPHERE
Recent studies indicate the ancient moon may have been home to a conventional collisional atmosphere created through volcanism and outgassing some 3 Ga ago. If this were the case, we can expect atmospheric volatile cycling and clouds within the atmosphere. As a first step towards understanding what a Lunar atmosphere might look like, we are investigating the nucleation properties of Lunar simulants under Earth atmospheric conditions. From here we hope to investigate other possible condensates as determined from chemical equilibrium modeling and study nucleation under more realistic lunar atmospheric conditions.
CLOUD MICROPHYSICS ON TITAN
Titan, largest moon of Saturn, is the only astronomical body aside from Earth known to host a robust hydrological cycle, albeit one that centers on the phase change of methane rather than water. For 13 years the Cassini Mission orbited Saturn, collecting data on Titan and the Saturnian system. While storms, clouds, and seasonal atmospheric changes have been observed our understanding of how clouds affect the behavior of Titan’s atmosphere and methane cycle is far from complete. To this end, are using numerical models, constrained by Cassini observations, to investigate the microphysics and thermochemistry of clouds and precipitation on Titan to understand their physical properties, chemical composition, and effect on the lower atmosphere and surface.
(Image courtesy of NASA/JPL/SSI)
GET IN CONTACT!
Prof. Alexandria Johnson
Office: HAMP 4288
Department of Earth, Atmospheric, and Planetary Sciences
550 Stadium Mall Drive
West Lafayette, IN 47907