Glossary

Coriolis Effect, named after French mathematician and physicist Gaspard-Gustave de Coriolis, is the effect that the rotation of the earth has on the path of travel of a flying object like a bullet. You may think that the bullet travels so fast and for such a short time, that the rotation of the earth will not matter, but because the earth rotates a full rotation, points closer to the equator, travel much further distance in one day that points closer to the poles. For example, the entire circumference of the earth is about 25,000 miles long, so one point on the equator, travels 25,000 miles in 24 hour. That equates to 1040 miles per hour, or if we speak in the same units we use to measure bullet velocity, it is 1525 fps. So is you are shooting a bullet from a rifle and you are standing on the equator, that bullet is travelling an additional 1525 fps in addition to its muzzle velocity, in whichever direction the earth is spinning. To calculate this, would take hours, thankfully with modern ballistics software, some apps and shooting tech gadgets calculate this difference for you. Do not be concerned though, this hardly has any considerable effect at below 500 yards, so it is only with ultra long range shots that you need to start considering the Coriolis effect on the bullet path also.