Clouds serve as an atmospheric blanket that controls the Earth’s surface temperature
Climate change is shrinking the gap between the daily high and low temperatures in many parts of the world, according to a new study.
Researchers attribute this asymmetry to an increase in clouds during the daytime. Increased cloud cover reduces the amount of incoming solar shortwave radiation. It pulls down the rate at which the daily maximum temperatures rise, stated the study published in AGU Geophysical Research Letters.
The difference between the two, or the diurnal temperature range (DTR), impacts — seasons, crop yields, residential energy use and heat-stress-induced ailments.
The formation of clouds affects weather and climate on all levels of the atmosphere. Precipitation is influenced by the kind and volume of clouds that frequently form over a location. Temperatures on the planet’s surface may also be impacted by cloud cover.
Additionally, clouds serve as an atmospheric blanket that controls the Earth’s surface temperature. A part of the solar energy that strikes Earth during the day is reflected back into space by clouds. This regulates the Earth’s surface temperature and prevents it from becoming too warm.
Also, clouds can behave as a blanket, trapping heat on Earth by absorbing heat emitted by the planet’s surface. They return this heat to Earth, warming the lower atmosphere.
“Clouds are one of the big uncertainties in terms of climate projections,” said co-author of the study Dev Niyogi, a professor at the University of Texas.
Clouds play a vital role in the diurnal temperature variation by modulating solar radiative processes, which consequently affect the heat exchange at the land surface, he added.
The researchers analysed the DTR at the end of the 21st century to arrive at the conclusion.
The team simulated the complex interactions between land-surface and climate change using supercomputers. They analysed — land-use modifications (such as deforestation), soil moisture, precipitation, cloud cover and other elements that can impact local temperature.
The daily maximum and minimum temperatures are anticipated to continue to rise due to climate change. But the daily maximum temperature will do so at a slower rate, the researchers concluded.
In many regions of the world, the DTR will ultimately continue to contract, but the alterations will vary depending on various local conditions, researchers said.
The team concentrated on the Malaysian peninsula and the Kanto region of Japan. They ran different climate projections using 10 years from 2005-2014 as a baseline.
They discovered that in the temperate Kanto region and the more tropical Malaysian peninsula, the temperature difference narrows by about 0.5 degrees celsius and 0.25°C, respectively.
Researchers ascribe a significant portion of these changes to the higher daytime cloud cover that would be anticipated to form under these climatic circumstances.
The findings can aid in improving current global climate models and understanding how civilisation and the environment will be affected as the DTR continues to shrink, according to the researchers.
“It is very important to know how DTR will change in the future because it modulates human, animal and plant metabolisms,” said Doan Quang Van, the lead author of the study. It also modulates the local atmospheric circulation such as the land-sea breeze, he added.
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