Backyard Science

with
Michelle Moody

“Low-Pressure” Weather Study
Nothing affects day-to-day life quite like the weather. The weather conditions outside can determine what we wear, what we do, and where we go. If it is cold and snowing outside, we will probably not put on flip-flops and work in the garden. If it is raining, the baseball game will probably get canceled.

An outdoor weather station is an engaging activity to add to your nature studies as we enter spring and summer. We will talk about the various weather conditions we measure, and then we will build a thermometer your children can use as part of a weather station.

We will also look at ways to add weather observation to your family’s nature journaling activities.
Let’s get started with our weather study!

Let's get started with our weather study!
What is Weather?

Scientifically speaking, the weather is the atmospheric conditions in a place within a relatively small amount of time. These conditions might change hour-by-hour or minute-by-minute. It might be cloudy, cold, and rainy in the morning and hot and sunny by the afternoon.

Temperature, precipitation, cloud cover, wind, barometric pressure, and humidity are all atmospheric conditions that we can measure to describe and predict the weather.

What is Temperature?

Temperature is how hot or cold something is as measured by a thermometer. Air temperature is probably the first weather condition you check each day. The temperature will determine if you wear a coat or not, or maybe if you go outside at all! The temperature affects if and how many people do their daily activities.

The atmosphere’s temperature, or air, is determined by the sunlight present. The more sunlight reaches the Earth, the higher the temperature. When rays of sunlight hit the Earth, it warms up, which in turn warms the atmosphere. Heat can build up over time, which is one of the reasons why the shorter days of winter are colder than the longer days of summer.

The temperature of the Earth’s atmosphere is also determined by the angle at which the sunlight hits the Earth. No matter the season—summer, winter, spring, or fall—the same sun with the same amount of brightness shines on the Earth. If the sunlight is just as bright at all times of the year, why are the temperatures so different?

The sun is directly overhead in the summer, and its rays directly hit the Earth. In the winter months, the sun sits lower on the horizon. This causes the rays to hit it at an angle. It’s the angle of the rays of sunlight that makes the difference in how they heat the Earth.

The winter rays hit the Earth at such an angle that they travel a longer distance through the atmosphere than the rays’ direct path during the summer months. Because of the longer distance traveled, some of the heat is dispersed through the atmosphere. This makes the sunlight hitting the Earth cooler during the winter than during the summer.

Hands-on Activity:
Make a Thermometer

This was one of our favorite weather activities to do. If it’s a hot day, the thermometer starts out reading cooler inside because of the air-conditioning. But when it’s placed outside, it’s fun to watch the temperature rise and mark it on the bottle and index card.

You can also make the temperature rise and fall by placing the bottle in hot water and cold water. We opted to put the thermometer in the freezer, then took it out in the sun on a 50-degree day.

Let your children try different variations—ice water, hot water, outside in the sun, outside in the shade, in the freezer—so they can test their ideas.

Supplies:
Plastic water bottle
½ cup Rubbing alcohol
½ cup Water (room temperature)
Strong scissors or knife
Clear straw
Index card
Red food coloring
Playdough or clay
Tape
Instructions:

Fill the water bottle a little past halfway with equal parts of rubbing alcohol and room temperature water. You can also use ½ cup of each. (We wanted to see the mixture rise above the bottle, so we filled it slightly past halfway.)

Add a few drops of food coloring and mix it up.

Place the straw in the bottle and pack the playdough around the top. Ensure the straw is standing straight and there is an airtight seal. The bottom of the straw should NOT touch the bottom of the bottle.

Umbrella in the rain

Tape an index card to the back of the straw. Your children can mark where the water mixture level is as the thermometer begins to read warm enough to move past the seal.

Place the thermometer outside in a sunny place. If it’s cold outside, then you can place the thermometer in hot water, then in cold water to watch the temperature rise and fall.

Place the thermometer in the freezer for a few minutes, look at the mixture level. Then, take it out and place it at room temperature. What happens? How quickly did the liquid move?

Take it further! What happens when you place this mixture in the freezer? Does it freeze completely? (Hint: Rubbing alcohol only freezes at temperatures below 128 degrees Fahrenheit.)

What’s Happening?

As the sun or hot water heats the mixture in the bottle, the spaces between the molecules expand. Warmer mixture is less dense than when the mixture is colder. This causes the air pressure in the bottle to rise, so the mixture needs somewhere to go. The mixture moves up the straw. When the temperature of the bottle cools, the space between the molecules shrinks, so the water becomes more dense. This causes the water in the straw to move down. This process is called convection. (If you do not have a tight seal with the clay, the mixture will not move up the straw. As the molecules warm and the pressure builds, the air can escape through the leak around the neck of the bottle.)

Nature Journaling & Weather Study

After your family makes their backyard weather station, you can bring together nature journaling and weather watching.

Here are some observations your family can discuss and journal about:

Watch the bird activity in your yard, and if you have bird feeders, watch their behavior at the feeders. Does it change as the temperatures get warmer or colder?

What changes do you notice in animal behavior when the wind is high and the clouds are threatening, but it hasn’t started raining?

If you have bird feeders, how do their feeding behaviors change when it is rainy? Drizzly? Windy? Do they feed in pairs or groups more when the weather is bad? Do they take cover around plants?

When the weather forecast calls for a dramatic drop in temperature and/or possibly frozen precipitation, what kind of activity do you see in birds, squirrels, and other backyard animals? Journal what you see.

If you don’t have a birdbath or water dish for the birds and insects, make one, then track their activity based on the temperatures, the rainfall received in your area, and the wind speed. Do they drink the water more when rain has been scarce? When temperatures are above a certain level?

As your children are journaling on different days, note the wind. Are birds more vocal on windy days or less windy days?

On very hot days, do you see more or less animal activity?

As winter days give way to warmer days of April or May (depending on your location), what do you notice about animal behavior? Do you see more nest-building activity?

Do you hear more animal noises in warmer weather? Keep a list in your nature journal of bird calls you hear. Use one of the bird call apps on your phone to help your children identify the calls.

The weather not only affects us, it also affects animals. Keep a log of the key weather measurements and animal activity. After a month or more of journaling, ask your children if there are any patterns they notice. Keep this project going through multiple seasons to see what your family can learn about weather and animal behavior.

Enjoy the weather regardless of heat, rain, wind, ice, or brrrrrr, freezing temperatures.
Michelle Moody
M

ichelle Moody, is a veteran homeschooling mom and owner of Thehomeschoolscientist.com.

After earning a masters degree in child development and education, God’s plan took her into a 12 year biotechnology career. She came home to homeschool. Now, she has returned to her first love of helping children explore and discover the world God has gifted us. Besides homeschooling her own children, Michelle has taught in the traditional classroom, in co-ops, and on the mission field in Bangladesh.

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