A group of scientists stated that slight variations in the sun's energy output can greatly affect global weather patterns, such as the intensity of the Indian monsoon, and these effects can be predicted years in advance. The sun goes through an 11-year cycle marked by changes in sun spot activity that emit energy bursts. Despite the small difference in energy output between a solar maximum and minimum, determining how this variation impacts the Earth's climate has been a significant challenge for meteorologists. By analyzing a century of weather data and using intricate computer models, an international team of scientists, led by the National Center for Atmospheric Research (NCAR) in the United States, demonstrated that even a small increase in the sun's energy can strengthen wind and rainfall patterns. Julie Arblaster, a co-author of the study published in Science, stated that the impacts of small changes in the sun's output on the global climate system have been recognized for some time. The researchers discovered how small variations are amplified to create cooler sea surface temperatures in the tropical Pacific and increased rainfall away from the equator for the first time. They found that during times of high solar activity, the upper atmosphere heats up over the tropics, leading to changes in wind patterns and increased tropical rainfall. Additionally, more sunlight during solar maximum slightly warms ocean surface waters in the subtropical Pacific, where clouds are usually less common. This additional warmth causes increased evaporation, resulting in more water vapor. The additional moisture is transported by trade winds to the typically rainy regions of the western tropical Pacific, causing more rainfall. In the tropical eastern Pacific, sea surface temperatures decrease slightly, leading to conditions akin to a La Nina event. La Nina is the opposite of El Nino, causing wetter conditions in the western Pacific and drier conditions in parts of South America. The Indian monsoon and various other regional climate patterns are primarily influenced by the movement of air in the tropics and subtropics. Predictions about the solar cycle could assist meteorologists in estimating potential variations in circulation patterns, sea surface temperatures, and regional weather patterns. NCAR scientist Gerald Meehl, the lead author of the study, emphasizes the interconnectedness of the sun, stratosphere, and oceans, highlighting their impact on events like winter rainfall in North America. Understanding the influence of the solar cycle could enhance scientists' ability to forecast regional weather patterns in the coming decades. Currently, the sun is in a quiet phase following a solar minimum at the end of the previous year. The Space Weather Prediction Center at the National Oceanic and Atmospheric Administration anticipates the next solar peak in May 2013. Brad Carter, senior lecturer in physics at the University of Southern Queensland, Australia, stated that the paper is a valuable contribution to understanding the potential climatic impacts of solar activity. He emphasized that while solar activity may have some effect on climate, it is important to note that it is not the sole explanation for global warming in recent years. For more information, visit www.swpc.noaa.gov/SolarCycle/.