Frozen-in-field

{
  "id": "MLC-T-MET-010516",
  "term": "Frozen-in-field",
  "field": "Meteorology and atmospheric science",
  "definition": "A concept in magnetohydrodynamics describing how magnetic field lines are carried along with the flow of a highly conducting fluid, such as a plasma. In this condition, the fluid cannot easily move across the magnetic field lines, and the magnetic flux through any surface moving with the fluid remains constant. This principle, known as Alfvén's theorem, is applied to phenomena in the sun's corona and Earth's magnetosphere.",
  "url": "https://mlchart.com/terminology/meteorology/frozen-in-field/"
}