Tuesday, 28 July 2009
Weather is created by the Sun heating the Earth, which makes the air move around. This produces constantly changing conditions, from clear blue skies to gusting winds and deafening thunderstorms
The Earth is wrapped in a protective blanket of gases called the atmosphere. This blanket make life possible on the Earth. Our weather is created in the lowest layer
The atmosphere has 5 layers stacked on top of one another. The lowest, the troposphere, contain 75% of the atomsphere's gases. The air thin out as you head towards the exosphere & space
The main atmosphere gases are nitrogen & oxygen, which is vital for life. Small amounts of the other gases help to trap the Sun's heat and filter out harmful rays. The Earth's gravity keeps the atmosphere in place
The higher you go, the less oxygen there is. Mountaineers use bottled oxygen in the 'thin air' to assist them breathe. The air on the highest mountains contains about one third of the gases found at sea level
Clouds form in the lowest layer of the atmosphere. Planes can climb to the next layer, the stratosphere, to get above the clouds and avoid storms
Fish also need oxygen to live. They take oxygen from water using feathery structures called gills. As water passes over the gills, they filter off the oxygen
Wind is moving air. The wind blows when the Sun heats the Earth's surface unevenly. Moving air brings different sorts of weather such as clouds and rain
why do winds blow? Warm air weighs less than cold air and rises. Cooler air rushes in to fill the space left the warm air. This movement of air is what makes the wind blow!
credits: jen green - my first planet earth encyclopedia / weather shop articles / elizaberth anne viau / various sources
