22 July 2026

The severity of geomagnetic storms — magnetic disturbances in Earth’s outer atmosphere — is widely understood to reach an upper limit as the strength of the solar wind increases. But this upper limit is an illusion that results from uncertainty in the measurement of solar-wind strength as the true value regresses towards the mean.

‘Expert opinion’ and the figure are published under a CC BY 4.0 licence.ReferencesNational Research Council. Severe Space Weather Events: Understanding Societal and Economic Impacts: A Workshop Report (National Academies Press, 2008).Shepherd, S. G. J. Atmos. Sol. Terr. Phys. 69, 234–248 (2007).Article

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Borovsky, J. E., Lavraud, B. & Kuznetsova, M. M. J. Geophys. Res. Space Phys. 114, A03224 (2009).Article