water on earth

• What happens to water vapor as it rises in the air?

  It cools and condenses into water droplets, forming clouds.
• What occurs when water droplets in clouds become too big and heavy?


  They fall back to the ground, often as rain or snow.
• What is the term for water falling back to the ground from clouds?

  This is known as precipitation.
• What causes water to evaporate from water bodies and the ground?

  Heat from the Sun causes the evaporation.
• What are two sources of water vapor besides water bodies?


  Living things, such as plants and animals, also give off water vapor.
• What is pure water?


  Water that does not contain any other substances is known as pure water.
• Why is most water found on Earth not pure?


  Because water is able to dissolve many substances easily.
• What makes ocean water salty?


  The dissolved substances in the ocean make it salty.
• Why is rainwater not considered pure?


  Particles and minerals in the air dissolve in rain as it falls.
• What happens to rainwater when it reaches the ground?


  It dissolves minerals found in the soil or rocks.