All living things on Earth are found on or near the solid outer layer of the planet's crust, called the lithosphere. The hydrosphere, a layer of oceans, rivers and lakes, covers 75% of the lithosphere. Compared to the size of the Earth, the lithosphere is only a thin layer, several kilometers deep at most. The layer of air around the Earth is called the atmosphere. The water cycle describes how water travels through the atmosphere, hydrosphere and lithosphere. All living things need water; without the water cycle, life as we know it would not exist.
Living things also need energy to survive. That energy comes from the sun as radiant energy. It falls first on the atmosphere, then on the hydrosphere and lithosphere. But it's not absorbed evenly over the entire Earth's surface, which causes different conditions in the atmosphere at different places. The climate in the Amazon rainforest is very different from the climate at the North Pole. We refer to the areas affected by these varying conditions of the atmosphere as different climate regions.
Climate regions are the result of
A
living things existing only on the lithosphere.
B
the thickness of the lithosphere.
C
how water travels through the atmosphere, hydrosphere and lithosphere.
D
sunlight being absorbed unevenly across the Earth.
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