正在确认阅读权限…
Why Do Deserts Have So Many Sand Dunes?
为什么沙漠里有这么多沙丘？
-
Wind blows loose sand grains across flat desert surfaces.风将松散的沙粒吹过平坦的沙漠表面。
-
When wind slows near rocks or plants, sand piles up into dunes.当风在岩石或植物附近减弱时，沙粒堆积形成沙丘。
-
Dune shapes depend on wind direction, speed, and sand amount.沙丘形状取决于风向、风速和沙量。
-
Barchan dunes look like crescents and move slowly forward.新月形沙丘呈弯月状，缓慢向前移动。
-
Star dunes have several arms and form where winds shift often.星形沙丘有多个臂状结构，多形成于风向频繁变化之处。
-
Sand grains hop and bounce in a process called saltation.沙粒通过一种称为跃移的过程跳跃弹跳。
-
Dunes grow taller as more sand collects on the windward side.随着迎风侧不断积聚沙子，沙丘逐渐增高。
-
Some dunes move meters each year, reshaping the desert slowly.有些沙丘每年移动数米，缓慢重塑沙漠地貌。