Water never leaves the Earth. It is constantly being cycled through the atmosphere, ocean, and land. This process, known as the hydrologic cycle or water cycle, is driven by energy from the sun. The water cycle is crucial to the existence of life on our planet.
The Water Cycle
During part of the water cycle, the sun heats up liquid water and changes it to a gas (water vapor) by the process of evaporation. Water that evaporates from Earth’s oceans, lakes, rivers, and moist soil rises up into the atmosphere.�
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The process of evaporation from plants is called transpiration. (In other words, it’s like plants sweating.) Liquid water in the plants changes to water vapor and goes into the air.�
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Both transpiration and evaporation add water to the atmosphere.
As water vapor (in the form of gas) rises higher in the atmosphere, it starts to cool and become a liquid again. This process is called condensation. When a large amount of water vapor condenses into tiny water droplets or ice crystals, it results in the formation of clouds.
When the water droplets or ice crystals in the clouds gets too heavy, the water falls back to the earth. This is called precipitation. Precipitation falls to the ground due to gravity. �
What causes there to be different forms of precipitation? Temperature!
Click on this website for more information about precipitation: https://scijinks.gov/precipitation/ �
When precipitation falls on the land, some of the water is absorbed into the ground. This type of ground is porous. This forms pockets of water called groundwater. Most groundwater eventually returns to the ocean.
Porous ground means the soil is full of tiny, interconnected holes, or pores, that allow water to soak in and be stored underground. The level of porosity affects water drainage, plant growth, and even the stability of the ground.
If the ground is not porous, precipitation runs directly into streams or rivers and is called runoff.
Runoff is the water, usually from precipitation or melting snow, that flows over the surface of the land instead of soaking into the ground. This water travels downhill (due to gravity) and often ends up in rivers, lakes, or oceans. �
The sun is important to the water cycle because it’s the engine that powers the whole process.
The sun’s energy heats up water in oceans, lakes, rivers, and even soil. This heat causes water to evaporate — turning liquid water into water vapor (a gas) that rises into the atmosphere.�
The sun also helps drive transpiration, which is when plants release water vapor into the air.
Groundwater: when precipitation falls on the land, some water is absorbed into the ground.
Gravity: Gravity causes precipitation to fall down and water to flow downward on land.
Hydrosphere: the sum of ALL water on Earth, including water in the oceans, lakes, rivers, underground, & in the air. It also includes the water cycle.
The water cycle is the process or movement of water. VS The hydrosphere is all the water on Earth.
Geosphere: the Earth itself. The solid parts of Earth, including the rocks, minerals, landforms of the surface & interior.