The Abbe number, also known as the V-number of constringence of a transparent material,  is a measure of the material's dispersion (variation of refractive index versus wavelength), with high values of `V` indicating low dispersion. The following formula is used: `V_D=(n_D-1)/(n_F-n_C)`, where:

The Acceptance Angle in Optical Fiber is found using the following formula: `theta=1/n_0sqrt(n_c^2-n_(cl)^2)`, where:

The Air Pressure at Altitude calculator estimates the air pressure at altitude. 

The Anelastic Attenuation Factor, also known as Seismic Quality Factor, quantifies the effects of anelastic attenuation on the seismic wavelet caused by fluid movement and grain boundary friction. As a seismic wave propagates through a medium, the elastic energy associated with the wave is gradually absorbed by the medium , eventually ending up as heat energy.  This is known as absorption which will eventually cause the total disappearance of the seismic wave. The formula used is: `Q=2piE/(deltaE)`,  where:

The Apsis-Apocenter Minimum Speed calculator computes the minimum speed in an orbit at apogee based on the semi-major axis (a), eccentricity (e), the mass of the primary body (M), and the Universal Gravitational Constant (G).