Draw the Fischer projections of the four aldotetroses. Draw the D sugar on the left and its L isomer directly to the right of it. Switch between an aldose and a ketose by clicking on \"switch carbonyl group.\" Add or delete carbon atoms using the add (\" \") or delete (\"x\") buttons. Clicking on a blue box once adds a hydrogen atom (H). Clicking on a blue box again toggles between H and OH.

a rain shadow is a dry region of land on the side that is protected against the prevailing winds of a mountain range. the prevailing winds are the winds that occur most of the time in a particular place of the earth

prevailing winds carry air toward the mountain range. as the air rises up over a mountain range, the air cools, water vapor condenses, and clouds form. on this side of the mountains, called the windward side, precipitation falls in the form of  rain  or snow. this dry air produces a  rain shadow.