Chapter 15 The Atmosphere Envol. Sci. II Mr. Martino

Lesson 1 – The Atmosphere Properties of the Atmosphere ◦ Atmosphere – thin layer of gases that surround the Earth ◦ Composition of the Atmosphere  Nitrogen – 78%; bacteria convert N 2 or nitrogen gas into a usable compounds called nitrates and nitrites through a process called nitrogen fixation  Oxygen – 21%; Oxygen gas built up over billions of years due to tiny photosynthetic organisms  Water Vapor – gaseous water found in the atmosphere

◦ Relative Humidity – the ratio of water vapor the air contains to the maximum amount it could have at that temperature  When humidity is high, sweat does not evaporate from the surface of the skin, therefore, perspiring does not cool us down  Condensation – process where water vapor quickly cools down on a surface that is colder than the air Condensation  Dew – when the air temp is warmer than freezing  Frost – when the air temp is below freezing  Cloud Formation – condensation that occurs in the air on tiny particles (particulates ) that are in the air such as salt crystals, smoke, and dust Cloud Formation

◦ Air Temperature  Temperature varies on the Earth due to the different angles in which the sun’s rays strike it ◦ Air Pressure – the force exerted by air on the area below it  Measuring air pressure – barometer  Mercury barometer – air pressure pushes mercury up the column in a tube, the greater the pressure, the higher the mercury will rise in the tube; inches  Aneroid barometer – metal chamber whose walls bend in when air pressure is high and bulge out when air pressure is low; the bending of the wall moves a dial; millibars

Barometers

◦ Barometric Pressure and Forecasting  High Pressure – air pressure is pushing down on the column of mercury making it rise, thus pushing out the bad weather; nice day  Low Pressure – air pressure is not pushing down on the column of mercury making it fall, thus allowing the bad weather in; not so nice day  Altitude and Air Pressure  The lower the altitude, the higher the air pressure  The higher the altitude, the lower the pressure  Stack of books example; book on the bottom have more pressure exerted on them than books at the top

Layers of the Atmosphere The Troposphere – the lowest layer of the atmosphere directly above the ground  Contains the oxygen we need  Movement of air in the troposphere is largely responsible for the weather  11 km in height (7 miles) = thicker at equator  As height increases, temperature decreases  The top acts as a cap not allowing it to mix with the layer above

The Stratosphere – the layer of the atmosphere above the troposphere  (km) above sea level (7-31 miles)  The highest level of the stratosphere is warmer than the lower levels.  Ozone layer – gaseous oxygen found in the upper layers  Absorbs and scatters the UV rays in the stratosphere  Occurs naturally in stratosphere  Causes damage to lung tissue and impacts plant growth in the troposphere

The Mesosphere and Thermosphere ◦ Mesosphere – extends km (31-50 miles) above sea level  Air pressure is very low  Meteorites burn up entering the mesosphere making fiery trails Meteorites ◦ Thermosphere – begins about 80 km above Earth  Air is thin; temps. are very high  Aurora borealis (northern lights) Aurora borealis (northern lights)

The Troposphere and Weather Weather – atmospheric conditions over short time intervals Climate – pattern of atmospheric conditions in large geographical regions Example – the climate in London is moist and temperate, but the weather can be hot and humid on a summer day

Heat Transfer in the Troposphere Energy from the sun heats the atmosphere driving air movement influencing temperature and climate. ◦ Heat always moves from warmer to colder ◦ Radiation – transfer of energy through space  No direct contact with a heat source  Dark objects absorb more heat, while light objects reflect more heat

◦ Conduction – transfer of heat directly between two objects that are in contact with one another  Occurs between the surface of the Earth and the air directly above it ◦ Convection – transfer of heat by the movement of currents within fluid Convection Currents – sinking cool air and rising warm air; causes winds

Air Masses Air mass – temperature, humidity, and pressure are generally the same Front – boundary between air masses Warm Front – boundary where a mass for warm air is pushing a mass of cold air ◦ Warm moist air rises over the cold dense air creating light rain Cold Front – boundary where a mass of cold air pushes against warm moist air ◦ Cold air pushes the moist air up causing it to condense forming heavy precipitation

Pollution of the Atmosphere Sources of Air Pollution ◦ Air pollution – release of damaging materials into the atmosphere ◦ Emissions – the damaging substances Classes of Pollution ◦ Natural Processes – wind kicking up dust, volcanic eruptions, fires ◦ Human Sources – combustion of fossil fuels ◦ Primary Pollutant – released directly into the troposphere ◦ Secondary Pollutant – products of reactions between primary air pollutants in the troposphere Air Pollution

How Air Pollutants Affect You Respiratory Problems ◦ Dust particles get trapped in mucus secretions and hair lining of the respiratory tract  Makes you cough  Long term exposure leads to asthma, bronchitis, and emphysema Long term exposure leads to asthma, bronchitis, and emphysema Carbon Monoxide ◦ Bonds to hemoglobin in the blood, not allowing oxygen to bond to RBC’shemoglobin  Headaches, tiredness, nausea  Long term – heart disease  Heart must work harder to deliver the same amount of oxygen to starved cells

Cancer ◦ Long term exposure can cause cells to mutate and start to divide uncontrollably forming tumors  Benign or malignant Benign or malignant

15.3 Controlling Air Pollution The Clean Air Act ◦ First passed in 1963  Revisions in 1970 and 1990 set stricter air quality standards ◦ Protects and improves the quality of air in order to safeguard human health and the environment Provisions of the Act ◦ Limits emissions from vehicles and industries ◦ Limits the conc. Of specific air pollutants and particulate matter ◦ Allows people to sue industries for break rules ◦ Sets aside research funds for pollution control

Reduction in Air Pollutants ◦ Since its passing, the worst air pollutants have seen a decrease of 57%, even though there are more people Motor vehicles – catalytic converters in gasoline cars reduce air pollutant emissions catalytic converters Cleaner Gasoline – lead was a major component of gasoline prior to 1973, today, only trace amounts remain.

Ozone: A Success Story ◦ Ozone is a pollutant in smog in the troposphere, but absorbs UV radiation in the upper stratosphere.  The Ozone Hole  Area of lowered ozone concentration over Antarctica that occurs every year from August until October.  Choloroflourocarbons  Chemicals that are produced by aerosol spray cans and refrigerators; breaks down ozone by releasing Cl- into the atmosphere

◦ Montreal Protocol  Nations signed this in 1987  Goal was to reduce the CFC production