In the Southern Hemisphere, where the June solstice is known as the shortest day of the year, it marks the first day of astronomical winter, but the middle of winter in meteorological terms.
Backfill refers to products or materials used to fill excavations. The most common form is composed of a mixture of gypsum and calcium bentonite. Apart from filling holes, one of the primary purposes is to mantle sacrificial anodes under the ground.
Instant history bias, which especially occurs in hedge funds, is also called backfill bias because hedge fund managers may choose not report fund performance to a database from the fund's inception, but instead choose to backfill the database later when they have established a track record of success with a fund.