On the Life Cycle of a Shallow Cumulus Cloud: Is It a Bubble or Plume, Active or Forced?

David M. Romps aDepartment of Earth and Planetary Science, University of California, Berkeley, Berkeley, California
bClimate and Ecosystem Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California

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Rusen Öktem aDepartment of Earth and Planetary Science, University of California, Berkeley, Berkeley, California
bClimate and Ecosystem Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California

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Satoshi Endo cEnvironmental and Climate Sciences Department, Brookhaven National Laboratory, Upton, New York

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Andrew M. Vogelmann cEnvironmental and Climate Sciences Department, Brookhaven National Laboratory, Upton, New York

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Abstract

A cloud’s life cycle determines how its mass flux translates into cloud cover, thereby setting Earth’s albedo. Here, an attempt is made to quantify the most basic aspects of the life cycle of a shallow cumulus cloud: the degree to which it is a bubble or a plume, and active or forced. Quantitative measures are proposed for these properties, which are then applied to hundreds of shallow cumulus clouds in Oklahoma using data from stereo cameras, a Doppler lidar, and large-eddy simulations. The observed clouds are intermediate between active and forced, but behave more like bubbles than plumes. The simulated clouds, on the other hand, are more active and plumelike, suggesting room for improvement in the modeling of shallow cumulus.

© 2021 American Meteorological Society. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses).

Corresponding author: David M. Romps, romps@berkeley.edu

Abstract

A cloud’s life cycle determines how its mass flux translates into cloud cover, thereby setting Earth’s albedo. Here, an attempt is made to quantify the most basic aspects of the life cycle of a shallow cumulus cloud: the degree to which it is a bubble or a plume, and active or forced. Quantitative measures are proposed for these properties, which are then applied to hundreds of shallow cumulus clouds in Oklahoma using data from stereo cameras, a Doppler lidar, and large-eddy simulations. The observed clouds are intermediate between active and forced, but behave more like bubbles than plumes. The simulated clouds, on the other hand, are more active and plumelike, suggesting room for improvement in the modeling of shallow cumulus.

© 2021 American Meteorological Society. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses).

Corresponding author: David M. Romps, romps@berkeley.edu
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