Quantitative Analysis of the Equator and Breathing of the Envelope Interface

Within the envelope surface framework, the Envelope Interface is defined as a closed three-dimensional perceptual surface formed by the bending and closure of a Survey Line Spiral in a Navier-Stokes vortex field. The breathing of the Envelope Interface — periodic expansion and contraction — manifests on the measurement layer as alternating readings of the electromagnetic field: the expansion phase corresponds to the electric field, and the contraction phase corresponds to the magnetic field. Based on the definition of the Envelope Interface v2.0, the geometric properties of the Survey Line Spiral, the derivation of the Navier-Stokes equation within WQT, and the correspondence between the electromagnetic field and breathing, this paper establishes a quantitative analysis method for deriving the breathing physical quantities of the Envelope Interface and locating its equator from the measurable electromagnetic field distributions E(r) and B(r). This paper presents the inversion formulas for breathing frequency, breathing amplitude, breathing phase, and equator position, and discusses their application in Earth's magnetosphere and laboratory vortex systems. Keywords: Envelope Interface, equator, breathing frequency, electromagnetic field, quantitative analysis, reading inversion