Weather is what is happening in the sky outside right now. It can be sunny, rainy, cloudy, snowy, windy, or stormy. Weather changes from day to day and even from hour to hour. In the morning it might be rainy, but by afternoon the sun might come out! Weather is different from climate – climate is the average weather over many years. Which of these is a type of weather?

On a sunny day, the sky is clear and the sun is shining brightly. Sunny days are usually warm because the sun's rays heat up the ground and the air. The sun is a star that gives us light and heat energy. Sunny weather is great for playing outside, going to the park, or having a picnic. But remember to wear sunscreen to protect your skin! What should you wear to protect your skin on a sunny day?

Rain is water falling from clouds in the sky. Rain is part of the water cycle. The sun heats up water from oceans, lakes, and rivers. The water turns into vapor (a gas) and rises into the air – this is called evaporation. The water vapor cools and turns back into tiny water droplets, forming clouds – this is called condensation. When the droplets get too heavy, they fall as rain – this is called precipitation. What is the process called when water falls from clouds as rain, snow, or hail?

Clouds are made of tiny water droplets or ice crystals floating in the air. There are different types of clouds. Cumulus clouds are fluffy and white – they look like cotton balls and usually mean fair weather. Stratus clouds are flat and gray – they cover the whole sky like a blanket and often bring light rain. Cirrus clouds are wispy and high up – they are made of ice and often mean a change in weather is coming. Cumulonimbus clouds are tall and dark – they are thunderstorm clouds! What type of cloud is fluffy, white, and looks like cotton?

Snow is frozen precipitation. Snow forms when the air is very cold – below freezing (32 degrees Fahrenheit or 0 degrees Celsius). Water vapor in the clouds turns directly into ice crystals. These ice crystals stick together to form snowflakes. Every snowflake has six sides, and no two snowflakes are exactly alike! What happens to snow when the temperature rises above freezing?

Wind is moving air. Wind happens when air moves from an area of high pressure to an area of low pressure. The sun heats some parts of the Earth more than others, which creates differences in air pressure. Warm air rises, and cooler air rushes in to take its place – that moving air is wind! Wind can be gentle (a breeze) or very strong (a gale or hurricane). What tool do scientists use to measure wind speed?

Thunderstorms are storms with lightning, thunder, heavy rain, and strong winds. Lightning is a giant spark of electricity in the sky. Thunder is the sound that lightning makes. Lightning heats the air so quickly that it explodes outward, creating a loud boom! Even though lightning looks cool, it is very dangerous. A good rule is: "When thunder roars, go indoors." Where should you go during a thunderstorm?

Many places on Earth have four seasons: spring, summer, autumn (fall), and winter. Seasons happen because the Earth tilts as it travels around the sun. When your part of the Earth is tilted toward the sun, you get summer (warmer weather and longer days). When tilted away, you get winter (colder weather and shorter days). In which season do trees grow new leaves and flowers start to bloom?

Meteorologists (weather scientists) use special tools to measure weather. A thermometer measures temperature (how hot or cold it is). A rain gauge measures how much rain has fallen. A wind vane (or weather vane) shows which direction the wind is blowing from. A barometer measures air pressure – falling pressure usually means a storm is coming. What tool measures temperature?

Some weather is extreme and can be dangerous. A tornado is a spinning column of air that touches the ground – it looks like a funnel. Tornadoes have the fastest winds on Earth, up to 300 miles per hour! A hurricane is a giant spinning storm that forms over warm ocean water. Hurricanes have strong winds and heavy rain. Both tornadoes and hurricanes can cause serious damage. What should you do if a tornado warning is issued for your area?