The Water Cycle

What does life depend on?

Recycling chemical elements

Energy moves…

THROUGH an ecosystem

Nutrients…

CYCLE within an ecosystem

How do cycles relate to each other

They are interdependent

What does interdependent mean?

The major biogeochemical cycles—like the carbon, nitrogen, and water cycles—are not isolated but are deeply intertwined and influence one another.

What can each step in a chemical cycle be driven by?

Biological or purely physical processes

What is the primary physical phase in which water is used?

Liquid

How much of the biosphere’s water is contained in the ocean?

97%

How much of the biosphere’s water is in the glaciers and polar ice caps?

2%

How much of the biosphere’s water is in the lakes, rivers, and ground water?

1%

Where does the water come from and end up in evaporation?

Water evaporates from the land into the air and atmosphere

Where does the water come from and end up in condensation?

Water condenses from the water vapor into the clouds

Where does the water come from and end up in transpiration?

Water transpires from the plants surfaces into the air

Where does the water come from and end up in respiration?

Water respirates from the organisms into the air and atmosphere

Where does the water come from and end up in precipitation?

Water precipitates from the clouds on to the earth

All processes in the water cycle

Precipitation over water, Wind movements, Precipitation over land, Percolation through the soil, Runoff and groundwater, Evaporation from the ocean, Evapotranspiration through land and plants

What role does PRECIPITATION OVER WATER play in the water cycle?

• When clouds become saturated and the water droplets or ice crystals grow too heavy to remain suspended, they fall back to Earth as precipitation.

• Precipitation is greater over the ocean, accounting for about 78% of global precipitation, because the ocean is the Earth's primary source of evaporated water, with more water evaporating than falling as rain on land

What role does PRECIPITATION OVER LAND play in the water cycle?

• When clouds become saturated and the water droplets or ice crystals grow too heavy to remain suspended, they fall back to Earth as precipitation.

• Over land, evaporation exceeds precipitation, with the difference compensated by runoff (rivers and groundwater) that returns water to the ocean, thus completing the water cycle

What role do WIND MOVEMENTS play in the water cycle?

The primary agent for transporting water vapor and clouds around the globe. It influences every major stage of the cycle, including evaporation, transpiration, cloud formation, and precipitation. 

What role does PERCOLATION THROUGH SOIL play in the water cycle?

Percolation is the movement of water through the soil, acting as a natural filter, storage system, and distributor for the water cycle by replenishing groundwater, sustaining surface water flow, and providing water for plants.

What role does RUNOFF AND GROUNDWATER play in the water cycle?

• Runoff returns precipitation to the surface of the Earth as streams and rivers, eventually flowing into the oceans

• Groundwater stores water underground after precipitation infiltrates the soil, acting as a reservoir that can naturally discharge into surface waters or be used by plants.

• Together, these two processes are crucial pathways for moving water from the atmosphere and land back into larger water bodies, completing the continuous water cycle. 

What role does EVAPORATION FROM THE OCEAN play in the water cycle?

Transforms liquid ocean water into atmospheric water vapor, which then forms clouds and eventually precipitates as freshwater on land

What role does EVAPOTRANSPIRATION THROUGH LAND AND PLANTS play in the water cycle?

• The sun's energy heats water from soil, rivers, lakes, and other surfaces, turning it into water vapor that rises into the atmosphere (Evaporation)

• Plants absorb water through their roots and release it as water vapor through tiny pores on their leaves called stomata (Transpiration)