Differential analysis

{
  "id": "MLC-T-MET-004980",
  "term": "Differential analysis",
  "field": "Meteorology and atmospheric science",
  "definition": "A method of chart analysis in which one field is derived from others by graphical subtraction or addition, usually with the topographies of two isobaric surfaces. Subtracting the contours of a lower surface from those of an upper surface gives thickness lines, which act as mean-temperature isotherms for the layer. Conversely, a 500 hPa topography is built by graphically adding the 1000 to 500 hPa thickness pattern to a 1000 hPa topography.",
  "url": "https://mlchart.com/terminology/meteorology/differential-analysis/"
}