Spring is one of the four conventional temperate seasons, following winter and preceding summer. There are various technical definitions of spring, but local usage of the term varies according to local climate, cultures and customs. When it is spring in the Northern Hemisphere, it will be autumn in the Southern Hemisphere. At the spring equinox, days are approximately 12 hours long with day length increasing as the season progresses. Spring and “springtime” refer to the season, and also to ideas of rebirth, rejuvenation, renewal, resurrection and regrowth. Subtropical and tropical areas have climates better described in terms of other seasons, e.g. dry or wet, monsoonal or cyclonic. Often, cultures have locally defined names for seasons which have little equivalence to the terms originating in Europe.   In some cultureS in the Northern Hemisphere, the astronomical March equinox (varying between 19 and 21 March) is taken to mark the first day of spring, and the Northern solstice (around 21 June) is taken as the first day of summer. In other traditions, the equinox is taken as mid-spring. In the traditional Chinese calendar, the “spring” season (春) is not equivalent to the European spring but instead consists of the end of winter (from 4 February) and beginning of summer (to 5 May), roughly taking the equinox as its midpoint. Similarly, according to the Celtic tradition, which is based solely on daylight and the strength of the noon sun, spring begins in early February (near Imbolc or Candlemas) and continues until early May (Beltane).