Why is south island's west coast called the "wet" coast?
The South Island's west coast of New Zealand is commonly referred to as the "wet" coast due to its high annual rainfall. Several factors contribute to the region's wet climate:
1. Geographic Location: The west coast is situated on the western side of the Southern Alps, which act as a barrier for prevailing weather systems. As the moist air from the Tasman Sea approaches the mountains, it is forced to rise, resulting in the condensation of moisture and subsequent rainfall.
2. Orographic Effect: The Southern Alps, towering up to 3,724 meters (12,218 feet), create an orographic effect, meaning that as the air ascends the mountain slopes, it cools and releases moisture in the form of rain or snow. This effect enhances rainfall on the western side of the mountains.
3. Prevailing Weather Systems: New Zealand's location in the Roaring Forties, a belt of westerly winds in the Southern Hemisphere, exposes the west coast to weather systems originating from the Tasman Sea. These weather systems often bring moist air and precipitation to the region.
4. Rain Shadow Effect: On the eastern side of the Southern Alps, the weather systems descending from the mountains experience the opposite effect. As the air descends, it warms and becomes drier, resulting in the east coast of the South Island being significantly drier than the west coast.
Due to these factors, the west coast of the South Island experiences high rainfall throughout the year, earning it the nickname of the "wet" coast. The abundant rainfall contributes to the lush rainforests, glacial rivers, and dramatic landscapes that make this region unique.