Fun Science: Weather
Professor Gizmo (Amazing Science Presentations) gives expert video advice on: Why does thunder make noise?; Is it true that all snowflakes are different?; What makes rainbows? and more...
Why is it warm in the summer and cold in the winter?
It's warm in the summer, and cold in the winter because of the angle that the sun shines on the earth. If the sun is shining at a direct angle like it does in the summer, all of that energy from the sun is concentrated on one area, but if the earth tilts a little bit, the same spot of sunlight that was going this way and is now this way is spread out over a big area. So the same amount of energy is hitting a bigger area on the earth and that causes the sun to spread it's heat out. We get cold in the winter, and in the summer we get direct sunlight so it's much warmer.
Why does thunder make noise?
Well, when you have lightning you have thunder. The lightning is actually what causes the thunder. The lightning is this giant release of built up electricity in the sky and when that charge is released, it superheats the air and causes the air to expand, and that expansion just rushes through the whole area and carries that sound wave with it, and our ears pick it up as a big, loud, thundering crash.
Is there electricity in clouds?
Yes, there is electricity in clouds. As the air is being jostled around by thunder storms, a lot of it is uplifted. It pulls the air up into the sky and as it goes past water droplets and particles in the air, it creates an electric charge. So, the clouds become charged and the Earth has a different charge and if that charge gets big enough and that charge has to be released somehow, an electric lightening bolt will be produced.
Why does it rain?
Air can hold different amount of moisture, and as the air picks up more and more moisture, it will stay in there until the air cools. Once the air cools, it can't hold as much moisture. So therefore when it cools, and if there's particles in there like dust and dirt where the air can condense on, it forms rain drops, and if the rain drops are heavy enough, they'll drop out of the clouds and they'll fall to the earth as rain.
Is it true that all snowflakes are different?
Snowflakes are all different. The reason they're different is because as a snowflake forms, you have water molecules which are in the atmosphere, and they condense out onto other water molecules to start forming this snowflake. As each one forms, a different number of molecules will drop to form on it, different temperatures will cause part of it to melt again, and then refreeze again, and so there's no set pattern for this to happen. So every snowflake is going to be just a total random process of forming. They should be all different.
Where does the wind come from?
The wind comes from the earth itself. Near the equator its much warmer, so the sun hitting the equator creates warm heat to rise. When this heat rises and then moves towards the poles. And as it moves towards the poles it begins to fall. As that air falls it then hits the earth which is moving, and that causes the air to spin around as the earth is moving and as it is following and creates wind. Most of the wind in northern hemisphere heads towards from west to east and in southern hemisphere its mainly from east to west.
Why is the equator so hot and poles so cold?
The equator is so hot and the poles so cold because the sun's angle is more direct at the equator for most of the year. At the poles, it's only a certain small portion of the year when the earth's rays from the sun are a little more concentrated. In fact sometimes, during the year, the sun never shines on the poles. So that is definitely a cooling time.
What makes rainbows?
I don't know. Did you ever notice that you can only see a rainbow with the sun at your back? The sun is an important part of this, so the sun has to be shining. When else do you see rainbows? It's right after rain or right before rain. When you have your back to the sun, the sun is shining on the rain that's falling away from you. When the light passes through the raindrops it creates a prism effect where the white light is broken up into different colors. All of these thousands of raindrops that are falling to the earth are like a thousand little prisms that create this giant appearance of a rainbow. You can never get to the end of the rainbow, by the way, because as you move the prism effect also moves with you. So, you'll never find that pot of gold.
Why do clouds float?
Clouds don't really float. Actually, if you see a cloud in the sky, it's because at that height, the temperature, and the pressure creates enough happenings in the atmosphere to cause the water vapor to come up and it condenses and forms a cloud. When you say clouds float, have you ever walked in a fog? That's a cloud and those clouds are right down on the earth's surface.
Where do tornadoes come from?
Tornadoes come from Kansas. No, actually tornadoes are formed when you have a big mass of cold and warm air mixing together, and it starts as a little battle and you get these thunderstorms forming. But then above the thunderstorm you get this jet stream which is whipping along and as it comes along, it catches the air and starts it spinning like this and that creates a tornado. It takes a special set of circumstances to have this happen but that's what it is. And if you can't find it that way, go to Kansas.
What is a "jet stream"?
Jet stream is kind of like a big river of air. And it's very high in the sky. It is kind of a push of our weather, it gives our weather pushes. It's a strong stream of air flowing through the upper atmosphere. It's going very fast, could be hundreds of miles an hour. It causes some of the air below us to kind of take that effect. The jet streams can, move in a southerly direction and cause the air mass that's in the north to drop down. It can go up and cause the southern air, which is maybe warm, to move up. So the jet streams kind of pull our weather around the planet in different directions.
What is the hottest place on earth?
The hottest place on earth is El Azizia, Libya, and I guess it was 136 degrees there. That's pretty warm. Death Valley is a close second. Death Valley is a little bit further north of the equator than Libya. In that area, you have this area which is kind of surrounded by mountains. It's lower than the ocean level, and I think the heat must just build up in that area, and get kind of trapped in there. That's why that is a very hot area compared to Libya, which is closer to the equator, where you would expect the hottest regions to be.
What is the coldest place on earth?
The coldest place on the earth is Vostok and it's in Antarctica. It shouldn't be a surprise to anybody because Antarctica and the North Pole are the two regions of the earth where the sun has it's least direct effect and so it's going to be the coldest place on the earth.