Category Physics

What makes it snow?

Take a close look at some snowflakes. You can see that they aren’t drops, like rain; or lumps, like hail; or tiny beads, like sleet. They look more like little feathers.

Snow forms when water vapour in clouds freezes. It forms at the top of storm clouds where the air is colder. The frozen water drops grow as more water vapour freezes onto them. They turn into tiny, clear pieces of ice called snow crystals. A snowflake is actually a bunch of snow crystals.

When you look at a snowflake through a magnifying glass, you see a beautiful, lacy shape. Even when they may seem the same, no two snow crystals are exactly alike. Some are flat. Others are shaped like long needles. Most look like pieces of lace. Yet, in one way they are almost all the same. Almost all snow crystals have six sides.

Snow can form high in the sky even in summer. But when snow falls in summer, it melts and becomes rain as soon as it reaches warm air lower down.

Picture Credit : Google

What causes lightning and thunder?

Lightning and Thunder

A flash of light zigs and zags across the sky. Another flash zaps its way to the ground. A loud crack, boom, or rumble sounds soon after. The flash is lightning. The sound is thunder.

The flash we see when snakes through the sky lightning is really a huge electric spark. During a thunderstorm, each tiny drop of water in a cloud becomes electrically charged making the whole cloud charged. When this electrical charge becomes strong enough, it forms a huge electrical spark – lightning.

Lightning can travel in many ways. Sometimes a charge flashes from one place to another within a cloud. Other times, electricity rushes between two clouds with electrical charges. Also, lightning can strike the ground.

A flash of lightning heats up the air around it. The heated air spreads or rushes out in all directions. As it swells, it slams into cooler air, making it shake. This is what causes the sound of thunder.

Picture Credit : Google

What makes a Rainbow?

Long ago, people thought rainbows were magic. Some people believed a rainbow was a bridge that appeared in the sky when the gods wanted to leave heaven and visit the earth. Other people believed that if you could find the end of the rainbow – where it touched the earth – you would find a pot of gold.

Today we know that a rainbow is made by sunlight shining through drops of water. Sunlight looks white, but it is really made up of many colours. When sunlight enters a raindrop, it breaks up into lots and lots of colours, including violet, blue, green, yellow, orange, and red. We see these colours in the rainbow. But because the colours blend, we usually see only four or five of them.

For you to see a rainbow during a rain shower, the sun must be behind you, and the rain must be somewhere in front of you. Rays of sunlight break up into colours as they reflect off many drops of falling rain. Together they make a shimmering, curved, colourful rainbow. If the rain is heavy, one or both ends of the rainbow may appear to touch the earth, many kilometres apart.

Some rainbows form when it isn’t raining. Sometimes small rainbows appear in waterfalls, in sprays of water from the sea, or in fountains where the water shoots high.

Picture Credit : Google

Is rain recycled water?

Rain is recycled

Rain falls from clouds, but the water in the clouds comes from water on the earth. How does that happen?

The earth is covered with water – in lakes, streams, ponds, rivers, puddles, and huge oceans. Even the earth’s plants and animals have water in them.

Every day, the sun dries up huge amounts of this water, turning it into vapour. The warmth makes the vapour rise. It rises so high that it cools and forms clouds made of water and ice drops. As the drops get larger, they become too heavy to stay in the air. They fall as rain or snow.

Some of the rain and snow soaks into the soil and is used by plants. Some collects in streams or rivers that flow into the ocean. The sun warms it up and turns it into water vapour again. This water cycle happens over and over. The earth is always recycling its water!

Picture Credit : Google

What is Weather?

Weather

Somewhere on the earth right now, it is cloudy and rainy. Somewhere it is sunny. Somewhere it is dark, windy, and snowing.

What is the weather like today where you are? Is it raining? Does it look as if it’s about to snow? Is the sun shining?

Do you ever talk about the weather? Many people do. Almost everyone cares about the weather.

The weather affects us in many ways. Day-to-day changes in weather can influence how we feel and the way we look at the world. Severe weather, such as tornadoes, hurricanes, and blizzards, can disrupt many people’s lives because of the destruction they cause.

Weather doesn’t just stay in one place. It moves, and changes from hour to hour or day to day. Over many years, certain conditions become familiar weather in an area. The average weather in a specific region, as well as its variations and extremes over many years, is called climate.

There are six main components, or parts, of weather. They are temperature, atmospheric pressure, wind, humidity, precipitation, and cloudiness. Together, these components describe the weather at any given time. These changing components, along with the knowledge of atmospheric processes, help meteorologists – scientists who study weather – forecast what the weather will be in the near future.

Picture Credit : Google

What is Fog?

Eeee-rump! Eeee-rump! The sound of a foghorn echoes in the night. A thick, grey fog creeps in from the ocean and settles over the waterfront. You can hardly see your hand in front of your face. It seems as if you are in the middle of a cloud.

As a matter of fact, that’s just what fog is. It’s a cloud of tiny water drops that touches the earth, instead of floating high in the sky.

Like every other kind of cloud, fog forms when warm, moist air meets cool air. Fog often forms when warm, moist air passes over the cold water or an ocean, lake, or river. The warm air quickly cools. Then the water vapour in it becomes millions of tiny drops – a cloud that rolls in from the water and spreads out over the land.

Fog forms over the land in much the same way when ground that has been warm all day begins to cool off. As the warm air above the ground cools, the water vapour in the air turns into tiny drops of water. A fog hugs the ground.

Picture Credit : Google