Characteristics of the Atmosphere • It is a blanketof moisture-filled air that surrounds the earth. • It consists 78% nitrogen, 21% oxygen, 1% other gases (argon, carbon dioxide and water) • It has ozone in its upper layers which absorb harmful UV rays from the sun. • It protects us from meteors (they vaporize due to the friction with the atmosphere) Video • It keeps the earth warm enough for us to live as it helps trap heat.
Layers in Order…(starting from the Earth upwards) 1. Troposphere – up approx. 12 km • Closest to the Earth’s surface. • Where all weather takes place. • Air is in constant motion with both vertical and horizontal currents. • Pressure decreases as altitude increases. • Has very small amounts of ozone. 2. Tropopause • Contains more ozone than troposphere. • Is warmer than the troposphere because it absorbs UV rays from the sun.
3.STRATOSPHERE • 12-50 km above the Earth’s surface • Higher levels of ozone than any other layer 4.MESOSPHERE • Temperatures are very low here • 50 to 80 km above the earth • Very low density • Meteors from space usually burn up in this layer due to air friction
What is Ozone? • About 19-30 kilometres above the Earth is a layer of gas called ozone, which is a form of oxygen. • Oxygen = O2 • Ozone = O3 • Ozone is produced naturally in the atmosphere.
5.Thermosphere (AKA –Ionosphere) • 80 km to 500 km from Earth’s surface. • Fewest air molecules • Also called ionosphere b/c the Sun’s radiation causes particles to become electrically charged ions. • The Northern and Southern lights (aurora borealis) are produced by these ions. • These charged particles also reflect radio signals so they can travel around the world.
6. Exosphere • Outer limits! SPACE • The thinest, outermost layer of the atmosphere • Very few particles (few hydrogen particles) spread out very far. -DISCOVERY COMMERCIAL
THE CARBON CYCLE CHAPTER 2.5
A Little Background Info … Organic Substances: • Always contain atoms of carbon and hydrogen and often contain oxygen and nitrogen atoms. • EXAMPLES: • Proteins, sugars, and fats Inorganic Substances: • Matter that doesn’t contain a combination of carbon and hydrogen atoms • EXAMPLES: • Carbon Dioxide (CO2), water (H2O), and ammonia (NH3)
CYCLING OF ORGANIC MATTER • The materials used in building the bodies of living organisms are limited to the atoms and molecules that make up the planet. • To maintain life on Earth, matter must be recycled. • Every carbon atom is recycled time and time again into new life forms.
The Cycle of Matter Fox CO2 + Energy Rabbit Decomposers or Organic Matter Plant Leaves Feed Matter Decomposition Plant Roots Inorganic Materials Inorganic Molecules Bacteria
THE CARBON CYCLE • Carbon is an element • Carbon atoms are the basis for all living things (called organic matter) and for all matter that was once living (called detritus).
Carbon is stored in FOUR places: • Living things • The atmosphere • The ocean • The earth’s crust These storage places are called carbon sinks.
Carbon is removed from the atmosphere by plants when they photosynthesize to make sugar. Photosynthesis ReactantsProducts • 6CO2 + 6H2O + light = C6H12O6 +6O2 Carbon Dioxide + water + light = Sugar ( Glucose) + oxygen
Carbon is returned to the atmosphere by plants and by animals when they respire or exhale. Respiration ReactantsProducts C6H12O6 + O2 = CO2 + H2O Sugar + oxygen = carbon dioxide + water • Please fill in chart on page 62.
Photosynthesis and cellular respiration are complementary processes. • The carbon that they use is repeatedly cycled through both processes, this relationship is often called the CARBON CYCLE.
Most of the carbon that forms living organisms is released to the atmosphere or water as carbon dioxide from dead decaying organisms. • Under certain conditions the decay process is delayed, and the organic matter may be converted into rock or fossil fuels such as coal, petroleum and natural gas.
This carbon is not released until the combustion process takes place through burning the fuels.
Reservoirs for Inorganic Carbon • Carbon, when not in organic form, can be found in three main reservoirs (storage areas): • The atmosphere • The oceans • The Earth’s crust
The Ocean • Carbon is found in sea shells and bones. • When these fall to the bottom of the oceans and get covered with sediment, they decompose over millions of years to form oil (one of the fossil fuels).
(Millions of tonnes of soil) Shells and Bones Sink to the bottom of the ocean Covered by sediment (Millions of years) Form oil (example: Offshore drilling NFLD)
Reservoirs for Organic Carbon • Organic carbon is also held in reservoirs – the bodies of living things. • All living things die and decomposition eventually returns the carbon to the cycle in inorganic form.
One Important Exception • Bogs – store huge quantities of carbon in organic form. • Bogs have very little oxygen, therefore decomposition is very slow. • Carbon atoms may remain locked away in dead plant matter (peat) for many years in a bog. • When plants decompose in a bog, they form peat that can get trapped under sediments over millions of years and form coal (another form of fossil fuel)
PLANTS Die in a bog and form Peat Millions of years and tonnes of pressure form coal