1. A tundra is a type of biome where the tree growth is hindered by low temperatures and short growing seasons.
2. A savanna or savannah is a mixed woodland-grassland ecosystem characterised by the trees being sufficiently widely spaced so that the canopy does not close.
3. An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea.
When the sun, moon, and Earth are aligned, the tidal force of the sun works with the tidal force of the moon. The combined pull can cause the highest and lowest tides, called spring tides.
