cloud Archives - Astrobiology

Illustration of the thermal structure of Titan’s atmosphere and its atmospheric processes. It illustrates the high-altitude photochemistry of N2 and CH4, leading to the formation of more complex organic molecules, aerosols, and cloud systems. It also depicts surface–atmosphere interactions and highlights the methane cycle (evaporation, condensation, and precipitation). -- Nature via PubMed

Astrochemistry, Astrogeology, Biochemistry & Organic Chemistry, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Cryobiology, Icy Worlds, Saturn, Status Report, Titan, Water/Hycean Worlds & Oceanography

Titan’s Organic World

by Keith CowingMay 24, 2026May 24, 2026

Titan, Saturn’s largest moon, possesses a dense N2–CH4 atmosphere driving complex organic chemistry. The interplay among photochemistry, aerosol formation, organic cloud condensation, and surface deposition makes Titan a natural laboratory […]

Bright milky blue ribbons of water are visible along the coast along with patches of brown and green in some areas. Colorful waters swirl off the Mid-Atlantic coast in an image captured by the MODIS (Moderate Resolution Imaging Spectroradiometer) on NASA's Aqua satellite on May 3, 2026. NASA Earth Observatory/Michala Garrison Larger image

Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Gaia - Planetary Perspectives, Habitable Zones, Imaging & Spectroscopy, Microbiology & Virology, Plant Biology, Press Release, Water/Hycean Worlds & Oceanography

Orbital Biosignature Assay: Phytoplankton Bloom Off The U.S. Mid-Atlantic Coast

by Keith CowingMay 13, 2026May 13, 2026

Editor’s note: As we begin to study worlds in our own solar system that might have life we use our home world as a testbed for the various ways to […]

Liquid CWP distributions for different rotation periods (columns). The top row shows zonal mean values for MG (blue) and CARMA (red). The middle and bottom rows show annual mean maps for MG and CARMA. - astro-ph.EP

Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Exoplanets, -moons, -comets, Habitable Zones, Press Release

The Effect of Planetary Rotation Period on Clouds in a Global Climate Model with a Bin Microphysics Scheme

by Keith CowingMarch 7, 2026March 7, 2026

Clouds are the largest source of uncertainty in climate simulations. For exoplanets, cloud simulation is particularly challenging because of the lack of observational data to tune parameterized cloud models.

Retrievals of Cassini/VIMS occultation of Titan. Top left: observations and best-fit TauREx retrievals. Bottom left: breakdown of the extinction contributions in the tholin + CH4(l)(HITRAN) case. Right: Atmospheric properties inferred for the tholin + CH4(l) (HITRAN) case. The source for the opacity data (i.e, HITRAN or ExoMol) is important and can slightly change the best-fit spectrum and retrieval interpretation. Overall, the Cassini data is dominated by molecular absorption from CH4, CO, C2H6, C3H8 and extinction by hydrocarbon aerosols (tholins + CHCH4(l). The shape of the 3.4 µm absorption feature is likely best explained by the contribution of multiple species including some contribution from tholins. Overall, retrieval interpretations of Titan’s atmosphere are compatible with stratospheric inferences from previous works (see Figure B1). -- astro-ph.EP

Astronomy & Telescopes, Atmospheres, Climate, Weather, Biochemistry & Organic Chemistry, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report, Titan

Cloud and Haze Parameterization in Atmospheric Retrievals: Insights from Titan’s Cassini Data and JWST Observations of Hot Jupiters

by Keith CowingMay 27, 2025May 27, 2025

Context: Before JWST, telescope observations were not sensitive enough to constrain the nature of clouds in exo-atmospheres. Recent observations, however, have inferred cloud signatures as well as haze-enhanced scattering slopes […]

Schematic diagram of the analytical model (Eq. (11)) we use to understand the effect of cloud height and particle size on SNR. The left part of the diagram represents clear-sky and the right represents cloudy-sky. The solid horizontal line at the bottom of the diagram represents the planet’s surface, which has albedo (reflectivity) αs. The cloud layer has albedo αc and zero absorptivity. The arrows represent light moving through the atmosphere, with thickness corresponding qualitatively to intensity. The arrows get thinner from tail to head, representing absorption in atmosphere. The background red color shows the assumed vertical distribution of ozone, which is concentrated at a high altitude. -- astro-ph.EP

Astrochemistry, Astronomy & Telescopes, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Habitable Zones, Status Report

Clouds Can Enhance Direct Imaging Detection Of O2 And O3 On Terrestrial Exoplanets

by Keith CowingMay 13, 2025May 13, 2025

Clouds are often considered a highly uncertain barrier for detecting biosignatures on exoplanets, especially given intuition gained from transit surveys.

Triton and Pluto -- NASA

Astrochemistry, Astrogeology, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Icy Worlds, Interstellar, Pluto, Status Report, Triton

Clouds and Hazes in the Atmospheres of Triton and Pluto

by Keith CowingNovember 20, 2024November 20, 2024

Clouds and hazes are abundant in the thin and cold atmospheres of Triton and Pluto, where they are thought to be produced by interactions between atmospheric gases and ultraviolet photons […]