Christmas tree

A Christmas tree is a decorated tree, usually an evergreen conifer such as spruce, pine, or fir or an artificial tree of similar appearance, associated with the celebration of Christmas. Originally a Celtic custom, the Christmas tree developed in early modern Germany (where it is today called Weihnachtsbaum or Christbaum) with predecessors that can be traced to the 16th and possibly 15th century, in which devout Christians brought decorated trees into their homes. It acquired popularity beyond Germany during the second half of the 19th century, at first among the upper classes.

The tree was traditionally decorated with edibles such as apples, nuts, or other foods. In the 18th century, it began to be illuminated by candles which were ultimately replaced by Christmas lights after the advent of electrification. Today, there is a wide variety of traditional ornaments, such as garland, tinsel, and candy canes. An angel or star might be placed at the top of the tree to represent the archangel Gabriel or the Star of Bethlehem from the Nativity.

Christmas tree (disambiguation)

A Christmas tree is a festive decoration. It may also refer to:

Christmas tree (aviation)

A "Christmas tree" was a type of alert area constructed by the United States Air Force for the Strategic Air Command (SAC) during the Cold War. Oftentimes, bombers or tanker aircraft were stationed next to a readiness crew building (RCB), also known as "mole hole" facilities. The alert apron, also known as an alert ramp, received the name "Christmas tree" because it basically resembled a tree of the same name.

History

Before the development of the B-52 Stratofortress, aircraft such as the B-36 Peacemaker, B-50 Superfortress and B-47 Stratojet were parked on alert aprons at right angles. Due to the size of the aircraft, this created a problem in launching aircraft efficiently in the event of an emergency scramble, requiring a different solution to be devised. To fix this, aircraft were repositioned on specifically designed alert aprons arranged in herringbone configurations, which then allowed the planes to pull out onto the runway as quickly as possible.

This meant that the aircraft would be positioned at 45 degrees in relation to an alert apron center line leading to a short taxiway and then onto the nearest runway(s). Two aircraft would be positioned on either side of the center line, typically four deep on either side, with one additional aircraft being positioned directly aligned on the center line furthest back. The success of this formation also led to the adoption of the setup for the KC-97 Stratofreighter and KB-50 Superfortress aerial refueling aircraft. As newer bomber and aircraft eventually entered the SAC inventory, the "Christmas tree" aprons would be used by the B-47 Stratojet, B-52 Stratofortress, B-58 Hustler, FB-111, B-1 Lancer, KC-135 Stratotanker and KC-10 Extender aircraft.