Our Round Earth - its Atmosphere (1971)

air is made up of gases gases like oxygen carbon dioxide and nitrogen we can't see these gases but we can see other things in the atmosphere like dust smoke and clouds all these are parts of the atmosphere how important is the Earth's atmosphere think about clouds and what they're made of are clouds something like the spray from this waterfall are clouds something like this Mist can your breath be like a cloud what about fog fog and mist and spray and clouds are all made of tiny droplets of water water that rises into the air from Land and Sea clouds are part of the atmosphere and move move about with it as clouds move the tiny droplets of which they are made may become so big and heavy that they fall back to the Earth as rain or snow this brings Water to plants plants need water to grow in desert areas there are few clouds and hardly any rain not many plants grow here you may know that there are no plant PL at all on the Moon the Moon has no clouds or rain what about gases in the atmosphere are they important to living things plants need gases from the atmosphere gases like oxygen and carbon dioxide oxygen and carbon dioxide move into plants through tiny holes in leaves plants could not live without gases gases from the atmosphere also mix with water so water plants also depend on materials from the atmosphere to live and grow so do fish and other animals that live in water people can't get oxygen directly from water underwater swimmers carry it with them in air tanks people get oxygen directly from the atmosphere so do other animals that live on land traveling across the land we find differences in the atmosphere at different heights if you've ever been to the top of a tall mountain you may have noticed that it becomes harder to breathe and colder the higher you go it's because the atmosphere gets thinner as we move move higher into the atmosphere farther away from the earth the atmosphere becomes still thinner and there is less oxygen people flying at high altitudes would have trouble breathing except that passengers get air pumped into the cabin under pressure in case of an emergency passenger planes are packed with oxygen masks if for any reason air pressure should drop people can get the oxygen they need to breathe like [Music] this cabins of space Vehicles also contain their own supply of oxygen so that astronauts can breathe on the moon where there is no atmosphere astronauts carry tanks of compressed air on their backs these tanks are something like those skin divers wear underwater besides providing air to breathe these tanks have another purpose air in a space suit helps protect an astronaut from extremes of hot and cold in direct sunlight the surface of the Moon gets extremely hot hundreds of degrees above zero but wherever there's shade the moon gets extremely cold hundreds of degrees below zero it's because there's no atmosphere on the moon no atmosphere to block the sun's Rays or to spread warmth more evenly over the moon surface on the Earth where there is an atmosphere it doesn't get as hot or cold as it does on the moon the Earth's atmosphere protects us how perhaps you remember a time when you were enjoying the warm sunlight and then all of a sudden a cloud moved in front of the sun blocking its rays how did it feel then cooler because some sunlight was blocked by the clouds the sun's rays are also blocked by gases and by water and dust in the air this is one way the atmosphere protects the Earth another way it protects us is by the way it moves by winds you know how air from an air conditioner or fan can keep you cool you know how air from a heater or furnace can keep you warm wind currents in the atmosphere do the same thing they bring warm air to cold parts of the earth and cool air to warm parts of the earth wind currents keep temperatures on the Earth from getting as hot or as cold as temperatures on the moon all movement movements in the atmosphere though are not helpful winds can blow away soil and damage crops tornadoes violent whirling winds that move in a narrow path over the ground destroy crops and trees and buildings hurricanes are powerful wind storms that form out at Sea and sometimes move across the land photographs of hurricanes taken from high above the Earth are used to spot them when they're still far from Land This is a way of telling where hurricanes are and where they're going so that weathermen can warn people before a hurricane strikes predicting the weather is an important reason for studying the atmosphere men are trying to find out more about the atmosphere more about how it acts upon the waters and lands of the earth and how it's used by living things men are becoming concerned about ways in which we pollute the atmosphere [Music] what can man do to stop this pollution will the atmosphere always provide the gases needed by plants and animals will it always protect life on Earth what do you [Music] [Applause] think