This "instantaneous indication, then lag" behavior is both a strength and a weakness. For powered aircraft, a standard VSI is fine. But for gliders, it has a fatal flaw: control inputs fool the instrument .
Modern "varios" use solid-state pressure sensors, GPS, and accelerometers to compute not just vertical speed, but also (how fast you are climbing relative to the surrounding air) and relative wind . Yet, the fundamental algorithm—measure total energy change, filter out pitch-induced noise—remains unchanged from the 1960s glider revolution. Why "Variometrum" Still Matters The word itself suggests something grander than a gauge: metrum (measure) of varius (change/variety). The variometrum is not just a measure of altitude change; it is a measure of the atmosphere’s hidden structure. It reveals what the eye cannot see—invisible columns of rising heat, the subtle sinking of cold air over a forest, the wave-like ripple of air over mountains. variometrum
Enter the (also called a TE variometer or compensated variometrum ). The Principle of Total Energy The total energy of an aircraft is: [ E_{total} = E_{potential} (altitude) + E_{kinetic} (speed) ] This "instantaneous indication, then lag" behavior is both