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Abstract The radiative cooling rate in the tropical upper troposphere is expected to increase as climate warms. Since the tropics are approximately in radiative–convective equilibrium (RCE), this implies an increase in the convective heating rate, which is the sum of the latent heating rate and the eddy heat flux convergence. We examine the impact of these changes on the vertical profile of cloud ice amount in cloud-resolving simulations of RCE. Three simulations are conducted: a control run, a warming run, and an experimental run in which there is no warming but a temperature forcing is imposed to mimic the warming-induced increase in radiative cooling. Surface warming causes a reduction in cloud fraction at all upper-tropospheric temperature levels but an increase in the ice mixing ratio within deep convective cores. The experimental run has more cloud ice than the warming run at fixed temperature despite the fact that their latent heating rates are equal, which suggests that the efficiency of latent heating by cloud ice increases with warming. An analytic expression relating the ice-related latent heating rate to a number of other factors is derived and used to understand the model results. This reveals that the increase in latent heating efficiency is driven mostly by 1) the migration of isotherms to lower pressure and 2) a slight warming of the top of the convective layer. These physically robust changes act to reduce the residence time of ice at any particular temperature level, which tempers the response of the mean cloud ice profile to warming. Significance StatementHere we examine how the amount of condensed ice in part of the atmosphere—the tropical upper troposphere (UT)—responds to global warming. In the UT, the energy released during ice formation is balanced by the emission of radiation to space. This emission will strengthen with warming, suggesting that there will also be more ice. Using a model of the tropical atmosphere, we find that the increase in ice amount is mitigated by a reduction in the amount of time ice spends in the UT. This could have important implications for the cloud response to global warming, and future work should focus on how these changes are manifested across the distribution of convective cloud types.
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This content will become publicly available on March 1, 2026
Abrasion Effect on Heating Performance of Carbon Nanotube/Epoxy Composites
The effects of abrasion on the heating performance of carbon nanotube (CNT)/epoxy composites were investigated in terms of Joule’s heat, convective heat, and radiative heat under moderate-to-severe and localized abrasive conditions. While the overall heating behavior was characterized by the heating rate and the curvature of the transient response, a numerical solution of the heat equation was used to quantify convective and radiative heat transfers, incorporating the specific heat of each component, the convective heat transfer coefficient, and the Biot number. CNT reinforcement significantly improved wear resistance at a CNT concentration of 0.31 vol. %, but the presence of micro-voids led to a slight increase in wear rate with additional CNT inclusion. Using an equivalent circuit model, local and severe abrasion scenarios were analyzed to determine the variation in electrical conductivity with temperature at different degrees of abrasion, indicating the impact of scattering effects. This analysis provides valuable insights for estimating both wear resistance and the heating performance of self-heated surface materials, with potential applications in future space technologies.
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- Award ID(s):
- 1738802
- PAR ID:
- 10626300
- Publisher / Repository:
- Nanomater
- Date Published:
- Journal Name:
- Nanomaterials
- Volume:
- 15
- Issue:
- 5
- ISSN:
- 2079-4991
- Page Range / eLocation ID:
- 337
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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