The sun is a big mass of energy. The sun produces high energy protons, and the solar wind carries these protons towards our planet. However during solar flare activity, energetic protons are blown violently outwards.. sometimes towards earth. Energetic protons can reach Earth within 30 minutes of a major flare's peak. During such an event (big ones are also known as Solar Proton Events), Earth is showered with highly energetic solar particles (primarily protons) released from the flare site. When these protons arrive at Earth and enter the atmosphere over the polar regions, much enhanced ionization is produced at altitudes below 100 km. Ionization at these low altitudes is particularly effective in absorbing HF radio signals and can render HF communications impossible throughout the polar regions. This effect is called Radio Blackouts. This type of event is also known as a Polar Cap Absorption Event or PCA.
A solar radiation storm happens when an explosion (Solar Flare) on the Sun accelerates solar protons toward Earth. These protons stream past our planet where they are (mostly) deflected by Earth's protected magnetic field. There are five Radiation Storm Warning class levels issued by the Space Weather Prediction Center (SWPC). Each are listed below.
S5 - Extreme
S4 - Severe
S3 - Strong
S2 - Moderate
S1 - Minor
Click HERE for a description of each Radiation Storm Level class.
Satellite Proton Event
Proton events are almost always associated with energetic solar activity such as major flares. They are periods of increased proton bombardments at satellite altitudes. They can affect satellite transmission/reception if intense enough and can cause other satellite anomalies.
Proton events may affect the ability of a HAM operator to establish contact with a satellite, and may affect the quality of television signals received by satellite (ie. cable tv may be affected). Satellite proton events occur within a few hours of a major proton flare.