Sunny, Rainy, Windy, and Snowy Days - First Grade Science
Every morning when you wake up, you probably look out the window to see what the sky looks like and decide what clothes to wear for the day. You are checking the weather! Weather is the condition of the air outside at a specific time and place. It describes whether the air is hot or cold, dry or wet, calm or stormy, and cloudy or clear. Weather changes from day to day and even from hour to hour, creating a fascinating and ever-shifting natural environment that affects how people live, what clothes we wear, and what activities we enjoy outdoors.
The Ingredients of Weather
Meteorologists are scientists who study and forecast the weather. They examine four main physical ingredients to determine what kind of weather is happening.
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| THE FOUR INGREDIENTS OF WEATHER |
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| 1. TEMPERATURE How hot or cold the air is outside. |
| 2. WIND The speed and direction the air is moving. |
| 3. PRECIPITATION Water falling from clouds (rain, snow, sleet). |
| 4. CLOUD COVER How much of the blue sky is covered by clouds. |
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Exploring Common Weather Types
Across the year, you experience a variety of weather conditions, each bringing unique sensations, sights, and sounds.
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| MAJOR WEATHER TYPES |
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| SUNNY DAYS RAINY DAYS WINDY DAYS SNOWY DAYS |
| Clear skies; warm Clouds release dropsMoving air blowsAir below 0C|
| light; great for of water; puddles; kites, leaves; fluffy white|
| hats & sunglasses. boots & umbrellas. cool breezes. snow falls. |
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Sunny Days
On sunny days, there are very few clouds in the sky, allowing the sun's radiant heat and light to reach the ground. The air often feels warm or hot. Sunshine warms the soil, helps plants perform photosynthesis, and creates crisp, sharp shadows beneath trees and buildings.
Rainy Days
Rain occurs when invisible water vapor in the air rises, cools down, and condenses into billions of microscopic liquid droplets that form clouds. When these droplets bump into each other and become too heavy to float in the rising air currents, gravity pulls them down to Earth as raindrops! Rain fills lakes, waters farmers' crops, and washes sidewalks clean.
Windy Days
Wind is air in motion caused by the uneven heating of the Earth by the sun. On windy days, you can feel breezes pushing against your face, watch kites dance high in the air, and see colorful pinwheels spin. Strong winds can make a cool day feel much colder, an effect called wind chill.
Snowy Days
When the air temperature high up in the clouds and all the way down to the ground falls below freezing (0 degrees Celsius or 32 degrees Fahrenheit), falling water droplets freeze into delicate, six-sided ice crystals called snowflakes. Snow blankets the landscape in quiet white powder, crunching beneath boots and offering fun for building snowmen and sledding down hills.
Stormy Weather: Thunder, Lightning, and Hail
Sometimes weather becomes very intense, producing powerful atmospheric events called storms.
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| ANATOMY OF A THUNDERSTORM |
| |
| .-~~~-. |
| .- ~ ~-( )_ _ |
| / ~ -. <--- CUMULONIMBUS CLOUD |
| | + + + + + + | Tall, dark, towering thunderhead|
| \ - - - - - - / charged with electricity. |
| '--._____________.-' |
| / / /\ / |
| / / / \ / <--- LIGHTNING BOLT: Giant electric spark |
| / / / /\ heats air to produce THUNDER sound. |
| v v v v v |
| HEAVY DOWNPOUR RAIN & HAILSTONES |
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Lightning and Thunder
During a thunderstorm, electrical charges build up inside giant dark clouds. When the electrical charge jumps between clouds or strikes the ground, it creates a blinding flash of light called lightning. Lightning superheats the surrounding air in a fraction of a second, causing the air to expand explosively and creating the loud booming sound we hear as thunder!
Chapter Review Exercises
Question 1: What is the scientific definition of weather, and what are its four main ingredients?
Question 2: Explain how falling water droplets form into clouds and eventually fall as rain.
Question 3: Why does water fall as snowflakes instead of raindrops on cold winter days?
Question 4: What is lightning, and what causes the loud booming sound of thunder that follows it?
Solutions and Explanations
Solution 1: Weather is the day-to-day condition of the outdoor air at a specific time and location. Its four main ingredients are temperature, wind, precipitation, and cloud cover.
Solution 2: Water from oceans and puddles evaporates into invisible water vapor and rises into the sky. As it cools high up, it condenses into tiny liquid droplets that gather to form clouds. When the droplets combine, get heavy, and can no longer float, gravity pulls them down as rain.
Solution 3: Precipitation falls as snowflakes when the temperature in the clouds and all the way down to the ground is below freezing (0 degrees Celsius or 32 degrees Fahrenheit), causing water vapor to freeze into six-sided ice crystals rather than liquid drops.
Solution 4: Lightning is a giant electrical spark that discharges between storm clouds or between a cloud and the ground. It superheats the nearby air instantly, causing the air to violently expand and create shock waves that we hear as booming thunder.