Geomagnetic storm

{
  "id": "MLC-T-MET-001142",
  "term": "Geomagnetic storm",
  "field": "Meteorology and atmospheric science",
  "term_source": "Geomagnetic Storm",
  "definition": "In solar-terrestraial terms, a worldwide disturbance of the earth's magnetic field,\ndistinct from regular diurnal variations.\n\nMinor Geomagnetic Storm: A storm for which the Ap index was\ngreater than 29 and less than 50.\n\nMajor Geomagnetic Storm: A storm for which the Ap index was\ngreater than 49 and less than 100.\n\nSevere Geomagnetic Storm: A storm for which the Ap index was\n100 or more.\n\nInitial Phase: Of a geomagnetic storm, that period when there\nmay be an increase of the middle-latitude horizontal\nintensity (H).\n\nMain Phase: Of a geomagnetic storm, that period when the hori-\nzontal magnetic field at middle latitudes is generally\ndecreasing.\n\nRecovery Phase: Of a geomagnetic storm, that period when the\ndepressed northward field component returns to normal levels.",
  "references": [
    "NWS Glossary"
  ],
  "url": "https://mlchart.com/terminology/meteorology/geomagnetic-storm/"
}