What classification of solar flares affects communications the most?

Solar flares are classified based on their intensity and the amount of energy they release, which directly impacts their effects on Earth, particularly concerning communications. The X Class solar flares are the most intense type and produce the highest energy output. When an X Class flare occurs, it can significantly disrupt radio communications and navigation systems, as well as impact satellite operations.

Due to this high energy release, X Class flares generate strong bursts of radiation, which can penetrate the Earth’s atmosphere and induce significant ionospheric disturbances. This leads to widespread disruptions in high-frequency radio communications and can even affect GPS signals.

In contrast, M Class and C Class solar flares are less intense. While they can still cause some communications issues, especially during strong storms or in conjunction with other solar activity, they do not match the disruptive potential of X Class flares. There is no recognized Y Class in solar flare classification. Therefore, the classification that poses the greatest risk to communications systems on Earth is indeed the X Class.