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Recent surveys have revealed that planets intermediate in size between Earth and Neptune ('super-Earths') are among the most common planets in the Galaxy (1-3). Atmospheric studies are the next step towards developing a comprehensive understanding of this new class of object (4-6). Much effort has been focused on using transmission spectroscopy to characterize the atmosphere of the super-Earth archetype GJ 1214b (refs 7-17), but previous observations did not have sufficient precision to distinguish between two interpretations for the atmosphere. The planet's atmosphere could be dominated by relatively heavy molecules, such as water (for example, a 100 per cent water vapour composition), or it could contain high-altitude clouds that obscure its lower layers. Here we report a measurement of the transmission spectrum of GJ 1214b at near-infrared wavelengths that definitively resolves this ambiguity. The data, obtained with the Hubble Space Telescope, are sufficiently precise to detect absorption features from a high mean-molecular-mass atmosphere. The observed spectrum, however, is featureless. We rule out cloud-free atmospheric models with compositions dominated by water, methane, carbon monoxide, nitrogen or carbon dioxide at greater than 5σ confidence. The planet's atmosphere must contain clouds to be consistent with the data., We observed 15 transits of the planet GJ 1214b with the Wide Field Camera 3 (WFC3) instrument on the Hubble Space Telescope (HST) between 27 September 2012 and 22 August [...]

Equilibrium climate sensitivity refers to the ultimate change in global mean temperature in response to a change in external forcing. Despite decades of research attempting to narrow uncertainties, equilibrium climate sensitivity estimates from climate models still span roughly 1.5 to 5 degrees Celsius for a doubling of atmospheric carbon dioxide concentration, precluding accurate projections of future climate. The spread arises largely from differences in the feedback from low clouds, for reasons not yet understood. Here we show that differences in the simulated strength of convective mixing between the lower and middle tropical troposphere explain about half of the variance in climate sensitivity estimated by 43 climate models. The apparent mechanism is that such mixing dehydrates the low-cloud layer at a rate that increases as the climate warms, and this rate of increase depends on the initial mixing strength, linking the mixing to cloud feedback. The mixing inferred from observations appears to be sufficiently strong to imply a climate sensitivity of more than 3 degrees for a doubling of carbon dioxide. This is significantly higher than the currently accepted lower bound of 1.5 degrees, thereby constraining model projections towards relatively severe future warming., Ever since numerical global climate models (GCMs) were first developed in the early 1970s, they have exhibited a wide range of equilibrium climate sensitivities (roughly 1.5-4.5 °C warming per equivalent [...]

Seen from space, Earth can look dressed up or downright dowdy, depending on the location. In some spots, swathes of cloud cloak the dark ocean, offering a stunning contrast of [...]

Climate science needs more mathematicians and physicists. So say prominent climatologists who are trying to spark enthusiasm for their field in budding researchers who might otherwise choose astrophysics or cosmology. [...]

An evaluation of atmospheric convective mixing and low-level clouds in climate models suggests that Earth's climate will warm more than was thought in response to increasing levels of carbon dioxide. [...]

THE TOPIC IN BRIEF * Aerosol particles in the atmosphere influence clouds, and thereby climate, because they act as nuclei for cloud formation. * Computational models of climate systems have [...]

Sometimes the most fruitful discoveries are the most unexpected. The discovery of Lyman-a blobs, puzzling giant gas clouds seen in the young Universe, definitely falls into this class. If astronomers [...]

Saturn caught the attention of astronomers in early December 2010 when a small, prominent white spot appeared in its normally bland and hazy northern hemisphere. During the ensuing days, this [...]

The effects of change in the diurnal temperature range (DTR) relative to the changes in the cloud type were analyzed by using general circulation model (GCM) simulations. Results have shown that thick clouds and precipitation secondary to greenhouse gas are directly related to the decrease in the DTR. The enhanced greenhouse effect such as increased carbon dioxide promotes an increase in the concentration of cloud condensation nucleus which in effect decreases DTR through surface evaporative cooling.