Download 4.2 Water Cycle

Chapter 4 – Earth’s Water
Student Notes – Lesson 2: The Water Cycle
Main Idea:
Liquid water can evaporate and turn into water vapor. Water vapor in the air can form clouds, fog, rain,
hail, sleet, or snow.
Vocabulary
Condensation (190) – process of water vapor changing to liquid water
Sea breeze (192) – the movement of air from the water to land
Land breeze (192) – the movement of air from land to the water
Fog (194) –clouds that form near the ground
Precipitation (196) – water that falls from the air to the ground in the form of rain, hail, sleet, or snow
Water cycle (198) – continuous movement of water between Earth’s surface and air as it changes from
liquid to gas to solid to liquid.
What makes water change forms?
Main Idea:
Condensation occurs when a gas changes into a liquid. Evaporation occurs when water changes from a
liquid to a gas.
Supporting Detail:
1. Seasonal changes
a. As fall turns to winter, the cooling temperatures remove heat from liquid water causing
it to freeze into a solid form.
b. As spring arrive, temperatures increase causing the frozen water to melt into a liquid
form.
c. As spring turns into summer, the increased temperatures cause the liquid water to
evaporate and change into a gas form (water vapor)
d. As summer turns to fall, temperatures decrease. The water vapor condenses and falls
to the Earth’s surface as rain.
2. Changes of state
a. Water changes state for gas to liquid and from liquid to solid when heat is taken away
from water.
b. When heat is added to water, the reverse happens and water changes state from a solid
to a liquid or a liquid to a gas.
What happens to water after it evaporates?
Main Idea:
When water evaporates and becomes water vapor, it is carried around with the air.
Supporting Detail:
1. When water evaporates and becomes water vapor, it is carried around with the air.
a. Moving air is called a wind or a breeze
b. Winds can carry water vapors from one place to another.
2. Air is made up of tiny particles of nitrogen and oxygen.
a. As the particles are heated, they move faster and farther apart. As air warms up, it
takes more space
b. As air cools, the particles slow down and move closer together. They require less space
than warm air.
c. Cold air is more dense than warm air as there are more cold air particles in a defined
space than warm air particles in the same sized space.
d. Cold air is heavier than warm air.
e. Cold air sinks; warm air rises
3. Sea breezes
a. During the day, land heats up faster than water as the particles of land are closer
together than the particles of water thereby enabling the quick transfer of heat.
b. The land warms the air above it resulting in the land air to rise.
c. The cooler sea air moves in to fill the space left by the warm air rising.
4. Land breezes
a. As the night occurs, the land cools down faster than the water.
b. The air above the water is warmer than the air above the land.
c. Air above the water rises.
d. Cooler air over the surface of the land moves in to fill the void.
How do clouds form?
Main Idea:
Clouds are made up of tiny water droplets or ice crystals.
Supporting Detail:
1. Air is filled with water vapor. As warm air rises and cools, the water vapors condense around
tiny dust particles forming water droplets.
2. Clouds form when air rises and cools when:
a. It is pushed upward over the mountains
b. It is warmed by the sun near the ground and rises
c. Warm is pushed upward by cool air
3. Clouds are how high they are and what they are made of.
a. Cirrus clouds form high in the sky.
i. They are usually made of ice crystals
ii. They have fuzzy edges
b. Cumulous clouds and stratus clouds form lower in the sky.
i. Cumulous clouds are puffy clouds that appear to rise from a flat bottom
ii. Stratus clouds form in blanket-like layers at low altitudes
iii. They are made of water droplets and have sharp, well defined edges.
iv. They are darker than cirrus clouds because the sun light is unable to pass
through them
c. Fog are clouds that form near the Earth’s surface.
Will it rain?
Main Idea:
Precipitation falls as rain, sleet, hail, or snow
Supporting Detail:
1. Clouds are made of liquid water.
a. The water is in the form of very small, light drops
b. The drops are pulled down by their weight, but pushed back up by the wind.
c. As time passes, the drops collide with each other to form larger heavier drops
d. Soon, the drops become too heavy for the wind to keep them in the air. These drops
fall to the ground as precipitation.
2. When the temperature is cool enough for water drops to form but above the freezing point,
water vapors condense and become rain.
3. When the temperature falls below the freezing point, sleet, hail, or snow is formed.
a. When raindrops fall through a layer of very cold air, the drops change into tiny bits of ice
called sleet. Sleet only reaches the ground in a frozen state if the air temperatures near
the ground are cold.
b. Hail forms when drops of water collide with bits of ice. The drops freeze to the ice. The
wind pushes the ice up into the cloud until it is too heavy. The hailstone keeps growing
each time it is pushed up in the clouds.
c. Snowflakes are formed when air temperature is so cold that the water vapor turns into
a solid. The water vapors in clouds turn into crystals, a solid that has a repeating pattern
in its shape.
How is water recycled?
Main Idea:
Water changes form and moves from place to place in the water cycle.
Supporting Detail:
1. Water on Earth is never lost
2. It just changes form and moves from place to place
3. Water cycle is the continuous movement of water between the Earth’s surface and air as it
changes from liquid to gas to solid to liquid.
a. Water vapors evaporate from the ocean
b. The vapors condense and form clouds
c. Water falls downs as precipitation
d. The water runs down the land to the ocean
e. From the ocean, it evaporates again