Grade 4
The Human Knowledge Project
Unit 13 — Earth Systems, Weather, and Climate
Welcome back!
Our planet is constantly changing.
Wind shapes the land, rivers carve valleys, volcanoes build mountains, and weather changes from day to day.
Scientists study Earth's systems to better understand our planet and help people prepare for natural events.
Earth's Four Major Systems
Earth can be divided into four connected systems.
Geosphere
The geosphere includes:
- rocks
- mountains
- soil
- volcanoes
- Earth's crust and interior
It is the solid part of our planet.
Hydrosphere
The hydrosphere includes all of Earth's water.
Examples include:
- oceans
- rivers
- lakes
- glaciers
- groundwater
- water vapor
Water is constantly moving through the water cycle.
Atmosphere
The atmosphere is the layer of gases surrounding Earth.
It provides:
- oxygen for breathing
- protection from harmful sunlight
- weather
- climate
Without the atmosphere, life on Earth would not be possible.
Biosphere
The biosphere includes every living thing.
Examples include:
- plants
- animals
- fungi
- microorganisms
- people
Living things depend on the other Earth systems to survive.
Weather
Weather describes the conditions of the atmosphere over a short period of time.
Weather includes:
- temperature
- wind
- clouds
- rain
- snow
- humidity
Weather can change from hour to hour or day to day.
Climate
Climate describes the average weather of a region over many years.
Examples include:
- tropical climates
- deserts
- temperate forests
- tundra
Climate changes much more slowly than weather.
The Water Cycle
Water is always moving through Earth's systems.
The main stages include:
- evaporation
- condensation
- precipitation
- collection
The Sun provides the energy that drives the water cycle.
Landforms
Earth's surface contains many landforms.
Examples include:
- mountains
- valleys
- plains
- plateaus
- canyons
- islands
Wind, water, ice, and earthquakes can slowly change these landforms over time.
Natural Hazards
Some natural events can be dangerous.
Examples include:
- hurricanes
- tornadoes
- floods
- earthquakes
- volcanic eruptions
- wildfires
Scientists study these events to improve forecasting and help communities prepare.
Activity
Observe the weather for one week.
Record each day:
- temperature
- cloud cover
- precipitation
- wind
- any unusual weather
At the end of the week, describe the overall weather pattern.
Then identify which Earth systems were involved in your observations.
Practice
Answer these questions.
What are Earth's four major systems?
How is weather different from climate?
What are the four main stages of the water cycle?
Name five landforms.
Why do scientists study natural hazards?
How are Earth's systems connected?
Review
Today you learned:
- Earth is made of four connected systems
- weather changes over short periods
- climate describes long-term patterns
- the water cycle continually moves water
- landforms change over time
- scientists study natural hazards to protect people
Understanding Earth's systems helps us appreciate the complex planet on which we live.
Looking Ahead
Next we will study ecosystems and living things, discovering how plants, animals, and microorganisms interact with one another and with their environment.