That organization noted Cleveland could produce ash clouds rising more than 20, 000 feet above sea level.

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For instance, clouds rising in the troposphere, the lower level of the atmosphere where air mixes freely, will bump up against the boundary of the much more stable stratosphere, forming ripples in the process.

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Since rising air causes clouds to form (the risen air eventually cools to the temperature of its elevated surroundings, and any water vapour it contains thus condenses), the result would be more rain than would fall in the absence of the artificial aerosols.

ECONOMIST: Saturday-night showers

Ahead, rising into the stormy clouds, is Mount Ngauruhoe, the massive volcano better known in the films as Mount Doom.

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These are clouds of superheated gas rising above the Sun's surface, each of them larger than the Earth.

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Prairie landscapes from 1927 turn a train and tall grain elevators into minimal vertical and horizontal strokes, while roiling clouds and the engine's rising smoke prefigure familiar abstract elements.

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Such aerosol-induced clouds, however, would have silver linings if they formed near a hurricane because the rising air that created them would carry away heat that would otherwise be sucked in to fuel the storm.

ECONOMIST: Saturday-night showers