U.S. Department of Energy Office of Biological and Environmental Research

BER Research Highlights

Modeling Condensation in Thunderstorm Clouds
Published: June 29, 2017
Posted: January 23, 2018

Simple model of condensation may not be sufficient for moderate thunderstorms.

The Science
Condensation of water vapor to form and grow cloud droplets is one of the most fundamental processes of cloud and precipitation formation. It drives cloud-scale winds and vertical air motion through the release of latent heat and determines the strength of storm updrafts, the upward winds that enable cumulus clouds to grow into thunderstorms.

The Impact
Two methods of cloud droplet condensation in cloud models were compared for simulations of scattered thunderstorms. The more detailed explicit condensation method led to stronger vertical motion in the thunderstorm cores and more upper-level cloudiness. Adding the effects of explicit condensation to weather and Earth system models will improve their ability to predict details of thunderstorms, including rain amount.

Cloud models simulate condensation using two different methods. The first is the simple “saturation adjustment” method in which exactly water-saturated conditions are assumed inside liquid clouds--that is, relative humidity is assumed to be 100%. The second method is more detailed and calculates condensation explicitly using the model’s predicted relative humidity, allowing humidity to be larger than 100% inside clouds. These two methods were compared in model simulations of scattered thunderstorms using the “piggybacking” approach that robustly separates dynamical from cloud microphysical effects. The saturation adjustment method produced larger thunderstorm vertical velocities due to its greater latent heating during condensation, leading to the clouds having more buoyancy. There was also a large impact on upper-level anvil clouds. Simulations using the explicit condensation method had more numerous, smaller ice particles that fell out more slowly compared to the simulations using saturation adjustment, leading to thicker, longer-lasting upper-level clouds. These findings have implications for simulating convective storms since most models use the simpler saturation adjustment approach, while the explicit condensation method is believed to be more accurate. However, results depend somewhat on details of the aerosol particles ingested into storms that activate cloud droplets, and more detailed observations are needed to confirm the existence of these high relative humidities inside thunderstorm clouds simulated by the explicit condensation method. This suggests a need for improvements in our ability to measure humidity accurately inside clouds. These results also suggest that the simpler saturation adjustment method can be modified in a straightforward way to capture the effects of explicit condensation, which will be explored in future work.

Contacts (BER PM)
Shaima Nasiri
ASR Program Manager

Ashley Williamson
ASR Program Manager

(PI Contact)
Hugh Morrison
National Center for Atmospheric Research

This work was partially supported by the U.S. DOE ASR grant DE-SC0016476. WWG was also partially supported by the Polish National Science Center (NCN) “POLONEZ 1” grant 2015/19/P/ST10/02596. The National Center for Atmospheric Research is sponsored by the National Science Foundation.

Grabowski, W.W. and H. Morrison. "Modeling condensation in deep convection." Journal of the Atmospheric Sciences, 74: 2247-2267 (2017). [DOI: 10.1175/JAS-D-16-0255.1]

Related Links
ASR Highlight: Modeling Condensation in Thunderstorm Clouds

Topic Areas:

  • Research Area: Atmospheric System Research

Division: SC-23.1 Climate and Environmental Sciences Division, BER


BER supports basic research and scientific user facilities to advance DOE missions in energy and environment. More about BER

Recent Highlights

May 10, 2019
Quantifying Decision Uncertainty in Water Management via a Coupled Agent-Based Model
Considering risk perception can improve the representation of human decision-making processes in age [more...]

May 09, 2019
Projecting Global Urban Area Growth Through 2100 Based on Historical Time Series Data and Future Scenarios
Study provides country-specific urban area growth models and the first dataset on country-level urba [more...]

May 05, 2019
Calibrating Building Energy Demand Models to Refine Long-Term Energy Planning
A new, flexible calibration approach improved model accuracy in capturing year-to-year changes in bu [more...]

May 03, 2019
Calibration and Uncertainty Analysis of Demeter for Better Downscaling of Global Land Use and Land Cover Projections
Researchers improved the Demeter model’s performance by calibrating key parameters and establi [more...]

Apr 22, 2019
Representation of U.S. Warm Temperature Extremes in Global Climate Model Ensembles
Representation of warm temperature events varies considerably among global climate models, which has [more...]

List all highlights (possible long download time)