Transcript Weather
Atmosphere in Motion Chapter 16 Atmosphere • What is the atmosphere? – A layer of gases surrounding Earth – Composed of matter and has mass – Subject to the pull of gravity Atmosphere • Earth's Atmosphere is: A mixture of gases with some suspended solids and liquids. • Three common solids (aerosols)in atmosphere: • Ice • Dust • Salt - from ocean spray Gas Composition of Earth's Atmosphere • Nitrogen - 78% of atmosphere • Oxygen - 21% of atmosphere • Trace gases - 1% - Neon, Helium, Hydrogen, Methane, Carbon Dioxide Formation of the Atmosphere: • The Earth's atmosphere was formed by a process in which gases like carbon dioxide, water vapor, sulphur dioxide and nitrogen were released from the interior of the Earth from volcanoes and other processes. Atmosphere • Levels –Troposphere–Stratosphere –Mesosphere –Thermosphere –Exosphere Levels of Atmosphere • Troposphere- approx. ground to 10 kilometers ( approx 7 miles up) – The closest layer to the Earth. – Contains 75% of our atmospheres gases – Weather clouds and smog occur in the troposphere • The troposphere is the layer where most of the world's weather takes place. • Since temperature decreases with altitude in the troposphere, warm air near the surface of the Earth can readily rise, being less dense than the colder air above it. • air molecules can travel to the top of the troposphere and back down again in a just a few days. • vertical movement or convection of air generates clouds and ultimately rain from the moisture within the air, and gives rise to much of the weather which we experience. Stratosphere • approximately 10 km - 45 km up (approx 7miles-30miles) • The ozone layer is located here • the jet stream is located here • Little or no water vapor here • a layer in which temperatures rises with increasing altitude. • At the top of the stratosphere the thin air may attain temperatures close to 0°C. This rise in temperature is caused by the absorption of ultraviolet (UV) radiation from the Sun by the ozone layer. • Such a temperature profile creates very stable atmospheric conditions, and the stratosphere lacks the air turbulence that is so prevalent in the troposphere. • almost completely free of clouds or other forms of weather. • Mesosphere - approximately 45 km -95 km up (30 - 50 miles up) – the coldest part of the atmosphere Thermosphere • approximately 95 km -to 500 km (50 miles and up) – Warmest layer of the atmosphere. • lower layer of thermosphere is called the ionosphere IONOSPHERE • made of electronically charged particles. • reflects radio waves • In the daytime this layer interferes with radio waves since suns energy charges the particles to much and causes problems a lot of static. • At night it is less charged. This is why it is easier to hear AM radio late at night Exosphere • approximately 500 kilometers and beyond – Outer most layer of our atmosphere – Very few air molecules in this layer – No clear boundary between this layer and space