What solar phenomenon is characterized by increased energy and radiation from the Sun?

The phenomenon characterized by increased energy and radiation from the Sun is a solar flare. Solar flares are sudden bursts of brightness on the Sun’s surface that can release an enormous amount of energy, equivalent to millions of hydrogen bombs exploding at once. This release of energy occurs when the magnetic fields of the Sun become tangled and snap, allowing energy that has built up in the atmosphere to escape outward.

Solar flares can have significant effects on space weather, often sending powerful waves of radiation toward Earth. They can disrupt communications, GPS systems, and other technologies due to the high-energy particles they emit. This distinguishing characteristic of rapidly increased energy output clearly defines solar flares within the category of solar phenomena.

In contrast, sunspots are dark areas on the Sun’s surface caused by magnetic field fluctuations, but they do not release increased energy or radiation; rather, they are indicative of solar activity levels. Solar wind is a constant stream of charged particles released from the Sun's corona, while coronal mass ejections involve large expulsions of plasma and magnetic fields from the solar corona. Although both solar wind and coronal mass ejections impact the space environment, they do not specifically denote sudden increases in energy and radiation like solar flares do.