| Why does the wind blow? You know that wind is moving air. But what causes the air to move? It's the uneven heating of the earth's atmosphere. As the sun warms the earth's surface the atmosphere warms too. Some parts of the earth receive direct rays from the sun all year and are always warm. Other places receive indirect rays, so the climate is colder. Warm air, which weighs less than cool air, rises. The cool air moves in and replaces the rising warm air. This movement of air is what makes the wind blow. |
| Weird Plant What looks like an octopus and can live for 1,000 years? It's the odd Welwitschia (Well-WITCH-ee-a) plant, which grows in desert areas in Namibia and Angola, two contries in Africa. The Welwitschia has only two leaves that shred into many long, leathery pieces as they grow. Welwitschias provide shelter for small desert animals and are an important part of the web of life in the desert. |
| Reindeer Antifreeze Most animals don't eat moss. It's hard to digest, and it has little nutritional value. but reindeer fill up with lots of moss. Why? The moss contains a special chemical that helps reindeer keep their body fluids warm. When the reindeers make their yearly journey across the icy Arctic region, the chemical keeps them from freezing- much as antifreeze keeps a car from freezing up in winter. |
| Why doesn't snow melt on mountains? Since the top of a mountain is closer to the sun than the base is, the peak should be warm and toasty, right? Actually, the top is the mountain's coldest spot. Here is why: The dense thinner atmosphere near the peak traps less heat, and the temperature gets colder and colder the higher you go up. Above a certain point, called the snow line, snow never melts. So when it comes to mountains, snow doesn't always mean wintertime. |
| Amazing Heart Facts Hold your hand and make a fist. If you're a kid, you're heart is about the same size as your fist, and if you are an adult, it is about the same size as two fists. ******** The heart beats about 100,000 times in one day and about 35 million times in a year. During an average lifetime, the human heart will beat more than 2.5 billion times. ******* Give a tennis ball a good, hard squeeze. You're using about the same amount of force your heart uses to pump blood out to the body. Even at rest the muscles of the heart work hard--twice as hard as the leg muscles of a person sprinting. ******** The aorta, the largest artery in the body, is almost the diameter of a garden hose. Capollaries, on the other hand, are so small tht it takes tem of them to equal the thickness of a human hair. ********* Your body has about 5.6 liters (6 quarts) of blood. This 5.6 liters of blood circulates through the body three times every minute. In one day, the blood travels a total of 19,000 km (12,000 miles) -- that's four times the distance across the US from coast to coast. |
| Amazing Lightning Facts Average Lightning Stroke is 6 miles long. Lightning moves about 30,000 times as fast as a bullet. 44,000 lightning storms occur every day throughtout the world. Lightning strikes the earth 6,000 times a minute. Since your last breath, lightning has struck the earth 100 times. The temperature of lightning's return stroke can reach 50,000 degrees Fahrenheit. The surface of the sun is not even that hot! (around 11,000 degrees Fahrenheit). Average Thunderstorm is 6-10 miles wide. On average, thunder can only be heard over a distance of 3-4 miles depending on humidity, terrain, and other factors. Ligtning does strike twice and more. The Empire State Building for example, averages over 20 hits per year. Daytime lightning is difficult or impossible to see under local sun and/or hazy conditions. Night-time "heat lightning" can be seen up to 100 miles away (depending on "seeing" conditions. To estimate the distance between you and a lighting strike, count the number of seconds between when you see the lightning flash and hear the thunder. Each five seconds is roughly equivalent to one mile in distance, i.e. 10 seconds between flash and thunder means the lightning was about two miles away. |
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