Cloud Cover Behind Shrinking Daily Temperature Gap

December 12, 2023

An increase in clouds could explain the shrinking difference between the daily high temperature and the daily low in many parts of the world. The gap between the two, known as the diurnal temperature range (DTR), has a significant effect on growing seasons, crop yields, energy consumption and human health.

As part of a collaborative study, researchers at the Department of Earth and Planetary Sciences examined projections of the DTR at the end of the 21st century. They found that the shrinking difference could be due to the increase in clouds blocking incoming-shortwave radiation from the sun during the day.

Climate change is expected to increase the daily maximum temperature and the daily minimum, but the daily maximum temperature will increase at a slower rate due to the influence of clouds. The end result is that the DTR will continue to shrink in many parts of the world, but that the changes will vary depending on a variety of local conditions.

The study, published in the journal AGU Geophysical Research Letters, is the first to use high-resolution computer modeling to delve into the issue of the shrinking DTR, particularly how it is related to cloud cover.

“Clouds are one of the big uncertainties in terms of climate projections,” said co-author and Professor Dev Niyogi. “When we do this with a very high spatial resolution modeling framework, it allows us to explicitly simulate clouds.”