Grade by Grade
E. Earth and Space Systems · Air and Water in the Environment

Air, Water and Weather

E2.1 E2.3 E2.4 A1.3 A2.2 A3.1About 40 minutes
Learning goals
  • I can explain how moving air and the water cycle make our weather.
  • I can explain how temperature decides if we get rain, snow, freezing rain, dew or frost.
  • I can name tools that measure weather.
  • I can design, build and test a rain gauge or wind sock.
  • I can describe how weather forecasts and technology help people.

Words to know

weather
What the air is like outside: hot or cold, wet or dry, calm or windy, sunny or cloudy.
fog
A cloud that is down at the ground.
dew
Drops of water that condense on cool grass and leaves overnight.
frost
Thin ice crystals that form on cold surfaces when water vapour freezes.
freezing rain
Rain that falls as a liquid and freezes into ice when it touches cold ground, trees or cars.
rain gauge
A tool that measures how much rain has fallen, in millimetres (mm).
forecast
A prediction of what the weather will be like.
meteorologist
A scientist who studies weather and makes forecasts.

Toque or sun hat?

Every morning, you decide what to wear. A raincoat? Snow pants? Shorts? To decide, you need to know the weather.

Here is a secret: almost all weather is made of just two things you already know about. Air and water!

Remember from Grade 1

In Grade 1 you recorded the weather, read a thermometer in °C, and learned that precipitation is rain, snow, sleet or hail. Now you will find out why we get different weather.

Air makes wind

The Sun warms the land and water, and they warm the air above them. Warm air rises. Cooler air rushes in to take its place. That moving air is wind.

Wind can be a gentle breeze on a summer day or a strong winter wind that blows the snow into big drifts. Wind also pushes clouds across the sky and brings new weather to our town.

Wind blowing snow across a farm field and piling it into drifts against a wooden fence.
Strong winter wind is moving the snow. Notice how it has piled up in drifts against the fence. AI-generated image

Water makes clouds, rain and snow

Remember the water cycle? Water evaporates, condenses into clouds and falls as precipitation. That is weather happening!

The temperature of the air decides what kind of water weather we get:

WeatherWhat happensWhen
☁️ cloudswater vapour condenses into tiny drops high in the skyany season
🌧️ raindrops in clouds join and fall as liquidair above 0°C
🌨️ snowwater in very cold clouds freezes into ice crystals that fallair below 0°C
🧊 freezing rainrain falls as liquid, then freezes when it hits cold ground, trees and carswarm air up high, below 0°C at the ground
🌫️ fogwater vapour condenses into tiny drops near the ground: a cloud at the groundoften cool mornings, near lakes
💧 dewwater vapour condenses on cool grass overnightcool nights, above 0°C
❄️ frostwater vapour freezes into thin ice crystals on cold surfacescold nights, below 0°C
Water weather, and the temperatures that make it
Worked example

Let's figure out the weather

Early on an October morning, the car windows are covered in a thin layer of white ice crystals. It did not rain or snow last night. What is it, and how did it get there?

  1. It didn't rain or snow, so the water must have come from the air.
  2. The air always has invisible water vapour in it.
  3. The night was very cold, below 0°C, so the car windows got very cold.
  4. The water vapour touched the freezing glass and turned right into ice crystals.

It is frost. Water vapour from the air froze onto the cold car windows overnight.

Measuring weather

Scientists use tools to measure weather:

  • Thermometer: measures temperature in °C.
  • Rain gauge: measures how much rain fell, in millimetres (mm).
  • Wind sock or wind vane: shows which direction the wind is blowing.
  • Anemometer: measures how fast the wind is blowing. It has little cups that spin in the wind.

Weather stations all over Canada measure these things every day.

thermometertemperature (°C)rain gaugehow much rain (mm)wind sockwind directionanemometerwind speed
Four weather tools and what each one measures.

Technology and weather forecasts

A forecast tells us what the weather will probably be like. Meteorologists (weather scientists) make forecasts using:

  • weather stations that measure temperature, rain and wind,
  • satellites in space that take pictures of clouds,
  • radar that finds rain and snow,
  • and powerful computers that run programs (code!) to predict what will happen next.

In Canada, Environment and Climate Change Canada sends out forecasts and weather warnings, for things like thunderstorms, freezing rain and extreme cold. Families see them on weather apps, the radio and TV.

Forecasts help us every day. Families choose what to wear. Farmers decide when to plant. Schools decide about snow days. Warnings tell people to stay safe during a storm.

Be an engineer: design a weather tool

Engineers follow a design process:

  1. Ask: What problem are we solving?
  2. Imagine and plan: Think of ideas. Draw a plan. Choose materials.
  3. Create: Build it.
  4. Test: Try it out. Does it work?
  5. Improve: Change it to make it better, and test again.
Worked example

Let's design a rain gauge

Problem: We want to know how much rain falls in our backyard. Design a rain gauge from things at home.

  1. Ask: We need something that catches rain and lets us measure how deep the water is.
  2. Imagine and plan: A clear plastic bottle with straight sides works. A grown-up cuts off the top. Turn the top upside down and put it in like a funnel. Tape a ruler (or mm marks) to the side, with 0 at the very bottom. Weigh it down so it won't blow over: stand it in a pot of pebbles or sand, or tape it to a stake. (If the bottle has a bumpy bottom, or you put pebbles inside for weight, add a little water first, up to the start of the straight part, and mark that level as 0.)
  3. Create: Build it and put it outside in an open space, away from trees and roofs.
  4. Test: After it rains, read the water level on the ruler. Write it down.
  5. Improve: Did it tip over? Add more weight around the outside. Did leaves fall in? The funnel helps keep them out. Empty it after each reading.

A rain gauge is a clear, straight-sided container with a funnel on top and mm marks on the side. It measures how many millimetres of rain fell.

funnel (bottle top)10 mm20 mm30 mm40 mm50 mmruler markson the sideraincollects
A homemade rain gauge: a clear bottle, the cut-off top turned upside down as a funnel, and mm marks on the side. Here about 26 mm of rain has collected.
Just for fun

Why did the cloud stay home from school?

It was feeling a little under the weather!

Hands-on activity

Build and test a weather tool

Choose one (or both!).

Rain gauge. You need: a clear plastic bottle with straight sides, scissors (a grown-up cuts), tape, a ruler or a strip of paper with mm marks, and pebbles. Build it like the example. Put it outside and check it after each rain for one or two weeks. Record each amount in a chart.

Wind sock. You need: a paper cup or a tube made from paper, crepe paper or plastic bag strips, tape, string and a stick. Cut out the bottom of the cup. Tape strips around one end. Tie string to the other end and hang it from the stick. Take it outside. Which way do the strips blow? Is the wind strong (strips stick straight out) or gentle (strips hang down and flutter)?

Test it, then improve it. What change made it work better?

Safety: A grown-up does all the cutting. Don't go outside during a thunderstorm.

Your turn

1

What two things make almost all of our weather?

2

What is wind?

3

It is −5°C and precipitation is falling. Is it more likely rain or snow?

4

What tool measures how much rain fell?

5

What is fog?

6

Name one way a weather forecast helps people.

7

What are the five steps of the design process?

More practice: warm-up

1

What tool measures temperature?

2

What does a wind sock show?

3

Name one kind of precipitation.

4

What do we call a scientist who studies weather?

5

Does warm air rise or sink?

More practice: on your own

1

In the morning, the grass is wet but it did not rain. What is the water called, and where did it come from?

2

What is the difference between dew and frost?

3

Why is freezing rain dangerous?

4

Your rain gauge showed 12 mm on Monday and 7 mm on Thursday. How much rain fell in all?

5

Name two kinds of technology meteorologists use to make forecasts.

Challenge

1

Your rain gauge blew over in the wind and lost its water. Use the design process to improve it.

2

Why might it rain in Toronto while it snows in Thunder Bay on the same day?

3

How would your family's day be different if there were no weather forecasts?

Check your understanding

Quiz

1.

What is wind?

2.

The air is −10°C and precipitation is falling. It is most likely...

3.

Wet grass on a cool morning with no rain is called...

4.

Which tool measures how much rain fell?

5.

Which is used by meteorologists to make forecasts?

6.

In the design process, what do you do after you test?

7.

Fog is...

For parents and teachers

Big idea (E2.1, E2.3, E2.4): Weather comes from air and water: moving air makes wind, and the water cycle plus temperature makes clouds, rain, snow, freezing rain, fog, dew and frost.

Engineering (A1.3) and technology (A2.2, A3.1): Building a rain gauge or wind sock practises the design process. Talking about forecasts shows how technology (satellites, radar, computer models) affects daily life.

How to help: Look at a weather app or the radio forecast together and talk about the symbols. Notice dew, frost and fog on early mornings. Keep a rain gauge log for a couple of weeks and add up the totals.

Common difficulties:

  • Freezing rain vs sleet vs snow can be confusing; at this age it's enough to know freezing rain falls as liquid and freezes on contact.
  • Reading a homemade gauge: the 0 mark must be at the bottom of the straight part. Help your child read the level at eye height.

Safety: Do all cutting yourself. Stay indoors during thunderstorms.