St Elmos Fire during Aerial Refueling of E-4 by KC-135

A USAF KC-135 Aircraft is preparing to refuel a USAF E-4. The same airframe used as Air Force One. The weather that we were going through causes the differential static equalization between the two aircraft. Once the boom touches the receptacle of the E-4 the charges are equalized and the static stops. What you really cannot see in this video is the semi-transparent shaft of purplish/pink electrons moving between the two aircraft, this is commonly known as St Elmos Fire.