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Updated: Jul 12, 2026
06:27
Measurement of Aerosols Optical Thickness of the Atmosphere using the GLOBE Handheld Sun Photometer
Published on: May 29, 2019
Direct observations of excess solar absorption by clouds
Science (New York, N.Y.)
|March 17, 1995
Summary
Aircraft measurements show clouds absorb much more solar radiation in the tropics than models predict. This suggests a significant gap in understanding cloud radiation interactions and their impact on climate.
Area of Science:
- Atmospheric Science
- Radiative Transfer
- Cloud Physics
Background:
- Solar radiation absorption by clouds is crucial for Earth's energy budget.
- Current climate models often underestimate cloud radiative effects.
- Discrepancies exist between theoretical predictions and observed solar flux in cloudy atmospheres.
Purpose of the Study:
- To investigate the discrepancy between measured and modeled solar absorption by tropical clouds.
- To quantify the anomalous solar absorption using aircraft-based measurements.
- To assess the accuracy of current cloud radiation interaction models.
Main Methods:
- Conducted an in-situ cloud radiation experiment using coordinated stacked aircraft.
- Deployed identical instrumentation for precise solar flux measurements at various altitudes.
- Analyzed solar flux data to determine cloud forcing ratios at different atmospheric levels.
Main Results:
- Aircraft measurements revealed anomalously large solar absorption by tropical clouds.
- The observed ratio of cloud forcing at 20 km to the surface was 1.58.
- This ratio significantly deviates from the model-predicted value of 1.0.
Conclusions:
- There is a substantial difference between observed and theoretically estimated solar absorption by clouds.
- Current models inadequately represent the interaction between clouds and solar radiation.
- Further research is needed to improve the understanding and modeling of cloud radiative processes.
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