【Grade 4 Science】Mastering Weather Observations!

Hello everyone! Starting today, we’re going to learn all about "Weather Observations."
"I hope it’s sunny for our field trip," or "I wonder if it’s going to rain tomorrow?" We live our daily lives constantly checking the weather. In this chapter, we’ll explore the secrets of weather, such as how "sunny" and "cloudy" are defined, and the proper way to measure air temperature.

It might seem a little tricky at first, but you'll be just fine if you keep these key points organized. Since this topic is so close to our everyday lives, let’s have fun while we learn!

1. How is weather determined?

Have you ever looked at the sky and wondered, "Is it sunny today?" or "Maybe it's cloudy?" In the world of science, we actually determine the weather based on "how much of the entire sky is covered by clouds."

The Rule Based on "Cloud Amount"

The proportion of the sky covered by clouds, when the entire sky is represented as "10," is called "cloud cover."

  • "Sunny": When the cloud cover is 2 to 8.
  • "Clear": When the cloud cover is 0 to 1 (almost no clouds at all!).
  • "Cloudy": When the cloud cover is 9 to 10 (most of the sky is filled with clouds!).

【Key Point】
The trick is to look at "how many clouds there are"—not whether or not the sun is shining! Even if you can see the sun, if clouds cover 90% of the sky, it is considered "cloudy."

💡 Fun Fact:
Don't you think the range for "sunny" is surprisingly wide? Even if more than half the sky has clouds, as long as it's 80% or less, it’s still "sunny." Knowing this makes looking at the sky a bit more interesting, doesn't it?

2. How to Use a Thermometer Correctly

To understand weather, measuring the "air temperature" is essential. We use a "liquid-in-glass thermometer" to do this, but there are some important rules to follow to get an accurate reading.

Things to Remember When Using a Thermometer

1. Do not touch the bulb (the red round part at the bottom): Your body heat will transfer to the thermometer, and you won't get an accurate air temperature reading.
2. Read the scale from straight on: If you look at it from above or below, you won't be able to read the number correctly. Keep your eyes level with the top of the liquid.
3. Keep out of direct sunlight: If sunlight hits the thermometer directly, the heat will warm the thermometer itself instead of the air temperature.

"Ideal Locations" for Measuring Air Temperature

According to scientific rules, you should measure air temperature in a place that meets these conditions:
・1.2 to 1.5 meters above the ground (about the height of an adult's chest).
・In a place with good ventilation.
・In the shade.
・It's best to be over grass or similar surfaces to prevent heat reflection from the ground.

【Common Mistake】
If you measure the temperature near the ground on asphalt, the thermometer will pick up the heat radiating directly from the surface, resulting in a much higher reading than what you see on the weather forecast. Be careful!

3. Weather and Temperature Changes

The way temperature changes throughout the day varies greatly depending on the weather. Try to visualize a graph as you learn these patterns.

Sunny Days

・Big fluctuations: The temperature climbs steadily during the day and drops significantly at night.
・Time of peak heat: The temperature usually hits its maximum around 2:00 PM, shortly after noon (12:00 PM), when the sun is at its highest.
・Example: It was cool in the morning, but by lunch break, it was so hot I started sweating!

Cloudy or Rainy Days

・Small fluctuations: Because clouds block the sunlight, the temperature doesn't change much throughout the day.
・On a graph, the line looks almost flat.
・Example: From morning until evening, the same chilly temperature continues all day long.

【Memory Trick!】
Think of the sun as a heater. When the heater is on (sunny), the room warms up quickly. When it's off (cloudy/rainy), the temperature stays mostly the same.

4. Summary: Just Remember These!

Here are the "Important Points" from today's lesson:

✅ How Weather is Defined
・Cloud cover of 0–8 is "Sunny" (0–1 is "Clear").
・Cloud cover of 9–10 is "Cloudy".

✅ How to Measure Temperature
・Measure in the shade, at a height of 1.2–1.5m.
・Read the scale from straight on.

✅ Daily Temperature Changes
・On sunny days, fluctuations are large (peaking around 2:00 PM).
・On cloudy or rainy days, fluctuations are small.

Great job! You’ve mastered the basics of weather observations.
The next time you go outside, try looking up at the sky and asking yourself, "How much cloud cover is there?" or "What's the weather right now?" That is the best shortcut to improving your science skills!