Solar flares are an enormous release of energy throughout the atmosphere of our sun. Our sun's core is undergoing constant nuclear fusion which changes hydrogen to helium. This energy is then transferred out from the core to the different zones that constitute our sun's outer layers. We have the core, the radiative zone, the convective zone and the photosphere and its corona.
Solar flares are associated with sunspot activity. Sunspot activity or sunspot phenomena corresponds to the solar magnetic activity cycle, which is an eleven year cycle. This cycle is determined by the period between the highest or most abundant sunspot activity, which is called the solar maximum, and the lowest amount of sunspot activity which is called the solar minimum. Sunspots are located in or at the sun's photosphere and are formed by intense magnetic activity.
This intense and localized magnetic activity inhibits convection, which makes the sunspot area cooler than the surrounding area. Sunspots could be thought of as magnetic storms similar to hurricanes or tornadoes. Similar in physical structure to hurricanes they have vortexes that presumably create very powerful magnetic activity. Like tornadoes they are creating conditions where these vortexes are generating or sustaining this sunspot phenomena, but also like a tornado are concentrating the activity.
As we understand magnetism we know that it is electrical charges that have attractive and repulsive properties. So in these sunspot storms we have twisting and rotating and concentrated vortexes of this magnetic activity. What exactly causes solar flare is very technical. Scientist believe that it is caused by magnetic reconnection. Imagine super powerful magnetic fields that are trying to maintain their equilibrium under the conditions mentioned previously. Negative and positive charges or fields in a plasma state getting concentrated and disconnecting and reconnecting according to their specific fields until the actual reconnecting of fields causes the magnetic field energy to get converted into thermal or kinetic energy and give us a solar flare or coronal mass ejection.
Solar flares are classified or categorized according to their strength: A, B, C, M and X, with X being the most powerful. Solar flares eject ions, electrons, protons and atomic particles which could be simply called or referred to as solar storms that create geomagnetic storms or disturbances on earth. Solar activity, such as solar wind causes the aurora borealis or the northern lights in the northern latitudes but more intense geomagnetic storms caused by solar flares or coronal mass ejection can disrupt communications and even damage satellites in space. Power grids can also be effected. Astronauts and passengers or pilots flying in airliners at high altitudes can be exposed to abnormal amounts of radiation.