Chapter 17: the Atmosphere Structure and Temperature Notes

Chapter 17: The Atmosphere Structure and Temperature Notes

17.1 Atmospheric Characteristics:

 I. How does weather differ from climate?  Weather =the state of the atmosphere at any given place and time  Climate=based on observations of weather that have been collected over many years…helps describe a place. The most important measurable properties of weather and climate are: air temp, humidity, type and amount of precipitation, air pressure and speed and direction of wind. What is the composition of the atmosphere? Scientists believe that oxygen did not occur in the atmosphere until photosynthetic cells evolved.  The atmosphere is constantly exchanging material with the oceans and with living things on Earth’s surface. Air is a mixture of many different gases and particles.  Nitrogen makes up 78% of the atmosphere and Oxygen makes up 21%. The other 1% of dry atmosphere is mostly argon.  Carbon dioxide is a very small part of the 1%, but it is very important to life on earth.  Water vapor in the atmosphere varies and has a big effect on weather and climate.  It is the source of all clouds and precipitation.  Like Carbon dioxide, it helps absorb heat given off by Earth.  The atmosphere also contains dust particles, sea salt, smoke, soot, pollen and microorganisms. Ozone  Most Ozone is 10-50 km above earth’s surface.  UV radiation from the sun can split O2 into single oxygen atoms which react with O2 to make ozone.  Ozone is O3, not O2.  Ozone protects us from harmful UV radiation and earth would be uninhabitable without it.  Down in the troposphere, it is a pollutant.  Our primary pollutant is Carbon Dioxide which comes mainly from transportation. What is the structure of the atmosphere?  The atmosphere rapidly thins as altitude increases until there are too few gas molecules to detect.  Atmospheric pressure= weight of the air above you.  The atmosphere can be divided vertically into 4 layers based on temperature. 1. Troposphere= weather occurs here. temp. decreases as altitude increases 2. Stratosphere=ozone is here. Temp is -60 C until you get up to the ozone then it ↑. 3. Mesosphere= temp ↓ here. 4. Thermosphere=temp ↑

Warm up: Thursday December 9, 2010  1. What gas makes up 78% of our air?  2. What gas makes up 21% of our air?  3. What is the most important measurable properties of weather?  4. What was NOT in the earth’s early atmosphere?  5. Air molecules move from:____ to ____ (high to low OR low to high?)

 Go to corr5.wikispaces.com  Unit 9 Weather  3. National Geographic Seasons Reading  Under Extras, click on the link after the following sentence: Ever wondered what other people do to celebrate the seasons? Click here to find out!  On looseleaf answer the following:  How does Iraq celebrate the seasons?  How does Finland celebrate the seasons?  How does Mexico celebrate the seasons?  How does Peru celebrate the seasons?

Earth-Sun Relationships  The amount of solar energy received by the earth varies with : latitude, time of day, and season.  Unequal heating of the earth creates winds and drives ocean currents. Earth’s Motions  Rotation: spinning on its axis once every 24 hours.  Revolution: moves around the sun in its orbit every year. Seasons  Occur because Earth’s position relative to the sun is constantly changing.  If the earth were not tilted on its axis at 23.5 degrees, we would not have seasons. Summer Solstice  June 21 or 22  Northern Hemisphere is leaning toward sun  First day of summer  At the Arctic Circle on this day, daylight is 24 hours because the earth is tilted so the “top” is fully “lit”.

Winter Solstice  December 21 or 22  First day of winter  Earth is tilted AWAY from the sun. Equinoxes  Autumnal equinox is Sept. 22 or 23  Spring equinox is March 21 or 22  On these days the earth is tilted but NOT toward OR away from the sun.  Sun’s rays strike equator vertically. Review:  What is the general process that causes the seasons?  Is the Earth closer to the sun in the Northern Hemisphere's winter or summer?  What is the relationship between the Earth and the sun during each of the four seasons in your home region?