Particulate matter in the Venus atmosphere

Ragent, B.; Esposito, L. W.; Tomasko, M. G.; Marov, M. Ya.; Shari, V. P.; Lebedev, V. N.

doi:10.1016/0273-1177(85)90199-1

Cited by 83 publications

(41 citation statements)

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“…In particular the nature of the UV absorber leaving distinct cloud shaped marks on dayside images is not known [ Esposito et al , 1997]. Also, for mode 1 and 3 particles, compositions different from H 2 SO 4 solutions and including solid crystals have been proposed [ Ragent et al , 1985; Esposito et al , 1997]. In clouds models usually a mode 2′ is included that features a slightly larger modal radius and size variation than mode 2.…”

Section: Background and Theorymentioning

confidence: 99%

Venus surface thermal emission at 1 μm in VIRTIS imaging observations: Evidence for variation of crust and mantle differentiation conditions

Müller¹,

Helbert²,

Hashimoto³

et al. 2008

J. Geophys. Res.

112

114

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[1] The Venus Express spacecraft images the nightside thermal emissions using the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS). At 1.02, 1.10, and 1.18 mm, thermal emission from the surface is observed. The signal is attenuated by scattering and absorption in the dense atmosphere. The measured flux at the top of the atmosphere is positively correlated with surface temperature and surface emissivity. The surface temperature of Venus is relatively well constrained as being mainly a function of altitude with a gradient lesser or equal to the adiabatic lapse rate. This study examines the correlation of VIRTIS images showing a signal of the surface at 1.02 mm with viewing geometry, stray sunlight, cloud opacity, and topography and applies semiempirical relations to remove their influence. The remaining contrast can be either ascribed to surface emissivity or unexpected temperature variations. Temperature variations due to active volcanism are unlikely to be persistent over the time of observations; therefore, the mosaic of all processed images is here interpreted in terms of surface emissivity variation. The emissivity variation found is correlated with geomorphological features established from Magellan synthetic aperture radar images. It is generally lower at tessera terrain. Some, but not all, volcanic edifices show increased emissivity. Large lava flows in the Lada terra-Lavinia planitia region also show an increased thermal emission. This might indicate a more felsic surface composition of tessera highlands and large-scale extrusive volcanism of ultramafic composition. Motivation[2] The search for exoplanets yields an ever increasing number of known planets. With further improvements in observation techniques it will hopefully soon be possible to detect Earth sized planets orbiting their stars at distances where liquid surface water is stable. The special interest in planets with these attributes is of course motivated by the desire to find habitable planets or even life. Size and orbital distance comparable to Earth is by no means an ideal indicator of habitability as the Earth's neighboring planets demonstrate. Venus with eight tenths of Earth's mass and nearly three fourths of Earth's orbital distance is quite inhospitable. The surface of Venus is extremely hot owing to greenhouse climate imposed by its dense CO 2 atmosphere and sulfuric acid clouds. Surface and atmosphere are also dry compared to Earth [Taylor, 2006].[3] Comprehensive understanding of why Venus so utterly failed to become remotely habitable has not yet been achieved [Crisp et al., 2002]. One missing piece for the reconstruction of the evolution of Venus is global knowledge on the composition of the crust. The surface has been extensively mapped at radar wavelengths by the Magellan mission [Pettengill et al., 1991] which further revealed a unique geology [e.g., Saunders et al., 1991;Head et al., 1992;Solomon et al., 1992;Schaber et al., 1992;Phillips et al., 1992;Stofan et al., 1992Stofan et al., , 1997Hansen et al., 1997;Grimm...

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Section: Background and Theorymentioning

confidence: 99%

Venus surface thermal emission at 1 μm in VIRTIS imaging observations: Evidence for variation of crust and mantle differentiation conditions

Müller¹,

Helbert²,

Hashimoto³

et al. 2008

J. Geophys. Res.

112

114

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“…These data sets suggested that the main cloud deck ($ 48-70 km) is divided into lower, middle, and upper cloud layers (Knollenberg and Hunten, 1980;Ragent et al, 1985). The tropopause is located at around 60 km altitude at the base of the upper cloud layer (Tellmann et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

“…The vertical structure of the clouds was investigated in situ by Venera 8-14 landers and four Pioneer Venus descent probes (Ragent et al, 1985). These data sets suggested that the main cloud deck ($ 48-70 km) is divided into lower, middle, and upper cloud layers (Knollenberg and Hunten, 1980;Ragent et al, 1985).…”

Section: Introductionmentioning

confidence: 99%

The radiative forcing variability caused by the changes of the upper cloud vertical structure in the Venus mesosphere

Lee

Titov

Ignatiev

et al. 2015

Planetary and Space Science

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“…Previous measurements indicate that particulates in the atmosphere of Venus follow a trimodal size distribution [7]. The medium sized (∼ 2-3 m diameter) mode 2 cloud particles consist of highly concentrated sulphuric acid droplets.…”

Section: • Aerosols In the Cloud Layersmentioning

confidence: 99%