Transcript layer
Layers of the Atmosphere What are the layers of the atmosphere and how do they interact? PART ONE Background Info Earth’s atmosphere is held in place by gravity. The atmosphere protects life on the planet by absorbing ultraviolet radiation and by regulating temperature. There is no exact place where Earth’s atmosphere ends. Instead it just gets gradually thinner and thinner (less dense) until it merges with outer space where it consists mostly of interplanetary gases such as hydrogen and helium. Background Info (cont.) Although the density of air decreases with the increasing altitude, that is, the air gets “thinner”, the proportions of gases in the air remain relatively the same, at least in the lower layers. Water vapor is found in the atmosphere, but its concentration varies with weather and climate conditions. For example, air is generally dry over the southwestern states but relatively wet over the southeastern region, which includes the Florida Keys. Top Ten Gases in Our Atmosphere Reveal Earth's Atmosphere National Geographic NASA explains the Layers of the Earth Layers of the Earth’s Atmosphere Troposphere O to 12 km- layer closest to the earth (also known as the “lower atmosphere”. This layer holds the most dense composition of gases and molecules. tropo means – “turning” or “changing” 12 km above the equator or less than 9 km above Poles At the top of this layer temperature stays -60 °C Water here forms _thin_, feathery clouds of _ice_ _Rain_, _snow__, & _most_ _clouds_ occur in this layer The Troposphere is important because…almost weather is created within this layer. Weather is important because it starts the water cycle. Stratosphere 12 to 50 km –just above the troposphere (about 7 mi above sea level); only the highest clouds can be found here. Some aircraft fly in the lower stratosphere (in the jet stream) to escape the turbulence in troposphere. Air is more dry and less dense. strato- “layer” or “spread out” The _upper_ stratosphere is warmer than the lower stratosphere _Ozone_ is in the middle to top portion of the stratosphere. Ozone is a form of oxygen found in the atmosphere. The _ozone_layer_ (lays near the top of this layer) protects Earth’s living things from ultraviolet radiation from sun. Some say there is a hole in our ozone layer. It is not exactly a hole but a thinning of the ozone layer Mesosphere _50_ to _80_ km; lies just above the stratosphere (30-50 miles above sea level) This layer contains chemicals that absorb energy from the sun. Together the stratosphere and the mesosphere are called “middle atmosphere” meso - means “_middle_” Most _meteoroids_ burn up in the _mesosphere_, producing _meteor_ _trails_. Molecules in the air spread _farther_ apart. Temperatures approach _-90_⁰C Important in the atmosphere because… It protects Earth’s surface from being hit by most _meteoroids_ . Thermosphere above _80_ km; lies above mesosphere (starting about 50 miles above sea level); also called the “upper atmosphere” Any person traveling at an altitude or more than 50 miles above sea level is considered an astronaut. It has _no_ _definite_ outer limit. This layer can reach temperatures of _1,800_- 2000 ⁰C. Despite the high temperatures you would _NOT_ feel warm. Important in the atmosphere because… The _thermosphere_ extends out into _outer_ _space_ Space shuttles and some satellites orbit the Earth here. We view Auroras (_Northern_ _Lights_ or Aurora Borealis, which are magnetic particles located in the thermosphere) which take place here. Aurora Borealis What causes the Northern Lights? Aurora over Hancock, MI looking north, July 25, 2004, 2:18am Photos by Claudia Perko From http://www.geo.mtu.edu/weather/aurora/ Thermosphere (continued) This layer is divided into two sub-layers. The lower layer is called the ionosphere. – About 80 to 400 km above Earth’s surface – Northern Lights are located in this layer. Free ionic particles can be found in the mesosphere and the thermosphere. The ionosphere is important because it reflects radio waves, enabling much of our long-distance communication. The upper layer is called the exosphere, the outermost atmospheric layer. It has no definite outer limit, as it merges with space. Many satellites orbit Earth within the exosphere, usually at altitudes of from 300-600 miles above sea level – About 400 km outward for thousands of km Summarizer Journey Through Our Atmosphere BBC: Power of the Planet - Atmosphere (50 mins.) Mr. Parr's Layers of Atmosphere Song Let’s complete a graphic organizer to remember the layers.