Solar flares

A flare is defined as a sudden, rapid, and intense variation in brightness. A solar flare occurs when magnetic energy that has built up in the solar atmosphere is suddenly released.  Solar flares can vary in length and time, although scientists have found ways to calculate when one will occur and its basic effect.  These solar flares alter the balance of the earth because of the massive magnetic and heat waves that the flares can create.  The amount of energy released is the equivalent of millions of 100-megaton hydrogen bombs exploding at the same time.  Fortunately, the earths magnetic field and atmosphere protect us from the flares dangerous radiation.  

The direct effects of solar flares are mainly related to communications and radio transmissions.  Another effect that solar flares have upon the earth is that of auroras.  When some of the charged particles of the solar flare pass through the earths magnetic field and atmosphere, they get accelerated along the lines of the magnetic field and collide with the particles in the atmosphere which makes them glow. There are also health issues for airline pilots and astronauts. For those of us that spend most of our time on the ground, the magnetic field and the atmosphere block out almost all of the harmful radiation and charged particles. This is not the case when you go up in the atmosphere. Airline pilots that fly at great altitude, and especially near the poles, are exposed to more of these. The same goes for astronauts. This results in a higher incidence of cancer among airline pilots and cabin crew.


http://hesperia.gsfc.nasa.gov/sftheory/flare.htm
http://hesperia.gsfc.nasa.gov/sftheory/spaceweather.htm
http://curious.astro.cornell.edu/question.php?number=308