Weather - Chapter 1 Weather - Chapter 1

The The AtmosphereAtmosphere

What is weather? Refers to the state of the Refers to the state of the atmosphere at a specific time atmosphere at a specific time and place.and place. The one thing that you can The one thing that you can talk to anybody about!talk to anybody about! If you don’t like the weather If you don’t like the weather just wait around it will change!just wait around it will change!

1.1 The Air Around You1.1 The Air Around You Weather is constantly

changing

The atmosphere is the envelope of gases that surrounds the planet

Composition of the Composition of the atmosphereatmosphere

NITROGENNITROGEN (N (N22): ): 78%78% OXYGENOXYGEN (O (O22): ): 21%21% Other: Other: 1%1%

CARBON DIOXIDECARBON DIOXIDE WATER VAPORWATER VAPOR METHANEMETHANE ARGONARGON

PARTICLESPARTICLES (dust, smoke, salt, (dust, smoke, salt, chemicals) chemicals)

Atmosphere Atmosphere Characteristics Characteristics • Water vapor is the source of all

clouds and precipitation. Like carbon dioxide, water vapor absorbs heat given off by Earth. It also absorbs some solar energy.

OzoneOzone is a form of oxygen that is a form of oxygen that combines three oxygen atoms combines three oxygen atoms into each molecule (Ointo each molecule (O33). ).

If ozone did not filter most UV If ozone did not filter most UV radiation and all of the sun’s radiation and all of the sun’s UV rays reached the surface UV rays reached the surface of Earth, our planet would be of Earth, our planet would be uninhabitable for many living uninhabitable for many living organisms.organisms.

It forms when lightening It forms when lightening interacts with oxygen in the interacts with oxygen in the air.air.

1.2 Air Pressure1.2 Air Pressure Properties of AirProperties of Air

Because air has Because air has MASSMASS, it also has , it also has other properties, including other properties, including DENSITYDENSITY and and PRESSUREPRESSURE..

DensityDensity D = M/VD = M/V

Pressure- the force pushing on Pressure- the force pushing on an area or surface.an area or surface.

Air Pressure- The result of the Air Pressure- The result of the WEIGHT OF A COLUMN OF WEIGHT OF A COLUMN OF AIR PUSHING DOWN AIR PUSHING DOWN on an on an area. area.

Air pressure changes from day Air pressure changes from day to day. Denser air exerts more to day. Denser air exerts more pressure than less dense air.pressure than less dense air.

– Measuring Air Pressure• Barometer

– an instrument that is used to MEASURE AIR PRESSURE.

– Two common kinds:1. MERCURY Barometers-glass tube

open at the bottom end and partially filled with mercury

» Mercury is pushed higher with more air pressure.

2. ANEROID2. ANEROID Barometers-air tight Barometers-air tight metal chamber that is sensitive metal chamber that is sensitive to changes in pressure.to changes in pressure.

METAL SPRING AND DIALMETAL SPRING AND DIAL Fig 6, page 13Fig 6, page 13

Measuring air pressure - Measuring air pressure - unitsunits

Several different units usedSeveral different units used Most use – inches of mercury (Hg)Most use – inches of mercury (Hg)

Based on the height of the column of Hg in Based on the height of the column of Hg in a Hg barometer. “30 inches of mercury”a Hg barometer. “30 inches of mercury”

National Weather Service indicates National Weather Service indicates pressure as millibarspressure as millibars 1 inch of Hg = 33.87 millibars1 inch of Hg = 33.87 millibars

eg. 30 in Hg = eg. 30 in Hg = 33.87 millibars 33.87 millibars = 1,016 millibars

1 in of Hg1 in of HgHectopascal (symbol hPa) is a SI unit, Hectopascal (symbol hPa) is a SI unit, one millibar is

equivalent to 100 pascals or one hectopascal. 1mb = 1hPa

Altitude and Air PressureAltitude and Air Pressure Altitude and properties of AirAltitude and properties of Air

Altitude:Altitude: ELEVATION OR ELEVATION OR DISTANCE ABOVE SEA LEVELDISTANCE ABOVE SEA LEVEL

Altitude and Air Pressure/Density:Altitude and Air Pressure/Density: INVERSELY PROPORTIONALINVERSELY PROPORTIONAL

Increase in Increase in ALTITUDEALTITUDE = = Decrease in air Decrease in air PRESSURE,PRESSURE, LESSLESS air pushing down from air pushing down from aboveabove you. you.

Altitude and DensityAltitude and Density The density of air decreases as altitude The density of air decreases as altitude

increasesincreases. Air at sea level has more gas molecules in . Air at sea level has more gas molecules in each cubic meter than air at the top of a mountain.each cubic meter than air at the top of a mountain.

Air Pressure

measured in units of

measured with

decreasesas

Density decreases

Altitudeincreases

Millibars Inches of mercury Barometers

Aneroid

include

Mercury

Graphic Organizer

1.3 Layers of the Atmosphere1.3 Layers of the Atmosphere

Layers of the atmosphereLayers of the atmosphere There are 4 layers in There are 4 layers in

the atmosphere the atmosphere classified according classified according to temperature to temperature changes.changes.

They are the They are the troposphere, troposphere, stratosphere, stratosphere, mesosphere, and the mesosphere, and the thermosphere.thermosphere.

Troposphere

• This is the layer that is closest to the surface of the earth

• It’s elevation ranges from 0 to 12 km

• Weather only occurs here

StratosphereStratosphere This layer sits on top This layer sits on top

of the troposphereof the troposphere It’s elevation ranges It’s elevation ranges

from 12 km to from 12 km to around 50 kmaround 50 km

This layer contains This layer contains the ozone layer, the ozone layer, which protects the which protects the earth from ultraviolet earth from ultraviolet radiation from the radiation from the sun.sun.

MesosphereMesosphere This layer is above This layer is above

the stratospherethe stratosphere It’s elevation It’s elevation

ranges from 50 to ranges from 50 to 80 km80 km

This layer protects This layer protects the earth from the earth from getting hit from getting hit from asteroidsasteroids

Thermosphere Thermosphere This is the highest layer This is the highest layer of the atmosphereof the atmosphere

It’s height ranges from It’s height ranges from 80 to 400 km80 to 400 km

This is where most This is where most small meteorites burn small meteorites burn up and is also the up and is also the location in the location in the atmosphere that the atmosphere that the northern lights occur northern lights occur (aurora borealis)(aurora borealis)

It is divided into the It is divided into the ionosphere (lower ionosphere (lower layer) and exosphere layer) and exosphere (upper layer)(upper layer)

Changing TemperaturesChanging Temperatures The graph shows The graph shows

how how temperatures in temperatures in the atmosphere the atmosphere change with change with altitude. altitude.

Use it to answer Use it to answer the questions the questions that follow.that follow.

Changing TemperaturesChanging TemperaturesWhat two variables are being graphed? In what unit is each measured?

Changing TemperaturesChanging Temperatures

Temperature Temperature andandaltitude altitude degrees Celsius degrees Celsius and kilometersand kilometers

Graph AnalysisGraph Analysis What is the What is the

temperature at the temperature at the bottom of the bottom of the stratosphere?stratosphere?

Which layer of the Which layer of the atmosphere has theatmosphere has thelowest temperature?lowest temperature?

Describe how Describe how temperature changes temperature changes as altitude increases as altitude increases in the troposphere.in the troposphere.

1.4 Air Quality1.4 Air Quality Pollutants- harmful substances in the Pollutants- harmful substances in the

air, water and soilair, water and soil They can affect human health and They can affect human health and

other thingsother things

Sources of PollutionSources of PollutionNatural sources-Natural sources- forest fires, soil erosion and forest fires, soil erosion and

dust storms. Wind carries particles of mold and dust storms. Wind carries particles of mold and pollen. Volcanoes emit clouds of gas, dust, and pollen. Volcanoes emit clouds of gas, dust, and ash.ash.

Human activities-Human activities- farming, construction, burning farming, construction, burning of fossil fuels (coal, oil, gas, diesel fuel)of fossil fuels (coal, oil, gas, diesel fuel)

Fossil fuels produce a variety of pollutants Fossil fuels produce a variety of pollutants including carbon monoxide, nitrogen oxides including carbon monoxide, nitrogen oxides and sulfur oxidesand sulfur oxides

Smog and Acid RainSmog and Acid Rain

Burning of fossil fuels can cause smog and acid rainBurning of fossil fuels can cause smog and acid rain London-Type Smog-London-Type Smog- created when particles in coal smoke created when particles in coal smoke

combine with water droplets in humid aircombine with water droplets in humid air

Photochemical Smog-Photochemical Smog- brown haze formed by the action of brown haze formed by the action of sunlight on pollutants such as hydrocarbons and nitrogen sunlight on pollutants such as hydrocarbons and nitrogen oxides. This is a combination of ozone and other pollutants.oxides. This is a combination of ozone and other pollutants.

Acid Rain-Acid Rain- forms when nitrogen oxides and sulfur forms when nitrogen oxides and sulfur oxides combine with water to form nitric acid and oxides combine with water to form nitric acid and sulfuric acid.sulfuric acid.

Rain, sleet, snow, fog and dry particles can carry Rain, sleet, snow, fog and dry particles can carry these acids to trees and lakes.these acids to trees and lakes.

It can damage buildings and statues and can make It can damage buildings and statues and can make water inhabitable for plants and organism.water inhabitable for plants and organism.

Before and AfterBefore and After

Effects of PollutionEffects of Pollution Air pollution can Air pollution can

cause many cause many different problems. different problems. This table shows the This table shows the health effects of air health effects of air pollution. Pollen also pollution. Pollen also can cause difficulties can cause difficulties for people with for people with allergies.allergies.

Improving Air QualityImproving Air Quality The Environmental Protection Agency (EPA) The Environmental Protection Agency (EPA)

monitors air pollutants in the United States.monitors air pollutants in the United States. New model cars and power plants produce New model cars and power plants produce

fewer pollutants than older models.fewer pollutants than older models. Cities are still polluted because there are Cities are still polluted because there are

more power plants and cars with the more power plants and cars with the increase in population.increase in population.

Reducing pollution can be very expensive.Reducing pollution can be very expensive.