Unit 8: Weather and Climate- Part I
I The Earths Atmosphere is the thin layer
of gases surrounding the hydrosphere
(water) and lithosphere (crust).
A. Origin of the Atmosphere
See ESRT p.8
1. Most likely first formed from gases
released by volcanoes (outgassing).
· First composed of Nitrogen (N2), Water vapor (H2O), and Carbon Dioxide (CO2) and …
no Oxygen (O2)
2. one-celled living things used CO2 for photosynthesis and released O2 as a
waste product.
3. From ____ MYA to ____ MYA O2 combined with dissolved iron in the ocean to form iron oxide.
The “rusting of the oceans’.
This formed thick Banded Iron Formations all around the world.
banded iron formation - Google Search
When all the iron in the ocean was rusted…
4. O2 slowly built up in the atmosphere starting at about _____ MYA
(see ESRT p.9)
B. The Composition of Atmosphere today is about
· 78% N2,
· 21% O2,
· 1% other gases-
mainly Argon, Water Vapor (H2O), and Carbon Dioxide (CO2 )
(See ESRT p.1)
YouTube - Evolution of the atmosphere
C. Layers of the Atmosphere
(see ESRT p.14)
What holds an airplane up?
How high can an airplane fly?
Can it fly into space?
YouTube - Chuck Yeager Pushing The Limits (The Right Stuff)
1. Troposphere:
· From surface to about km. or mi. in altitude.
· Air temp. ______with increasing altitude.
· Contains all the water vapor, clouds, and weather. (ESRT p.14)
· Upper boundary called the Tropopause.
2. Stratosphere:
· Rises to about _____ km. or _____ mi.
YouTube - Flying to the Stratosphere (start 3:15)
· Temperature ______with increasing altitude.
· Upper boundary called the Stratopause.
· Contains the Ozone Layer of gases.
· Ozone (O3) absorbs dangerous ultraviolet sunlight and protects living things.
Human activities have decreased the amount of ozone.
This could endanger living things.
YouTube - Ozone layer (104)
3. Mesosphere:
· Rises to about _____ km. or _____ mi.
· Temperature ______with increasing altitude.
· Meteors burn up in this layer due to friction with air.
· This forms “shooting stars”.
YouTube - Perseid meteor shower
4. Thermosphere:
· Gradually blends into the vacuum of space.
· Temp. ______with increasing altitude.
· Contains Aurora’s or the Northern and Southern Lights. (see text p.688)
http://svs.gsfc.nasa.gov/vis/a010000/a010000/a010014/a010014_H264_640x480.mp4
[Lab: Temp. of the Atmosphere]
II Heat and the Atmophere
A. Air Temperature is measured using 3 scales: °F, °C, and °K
(See ESRT p.13)
Practice:
1. Each mark on the °F scale = _____
2. Each mark on the °C scale = _____
3. Each mark on the °K scale = _____
4. 60° F. = _____ °C. = _____ °K.
5. 10° C. = _____ °F. = _____°K.
6. 277° K. = _____ °C. = _____ °F.
7. 108° F. = _____ °C. = _____ °K.
B. How the atmosphere is heated:
1. Conduction: transfer of heat energy by direct collision of atoms. This usually occurs in Solids. (see text p.483)
Ex. Air is heated by touching the warm ground.
[Diagram]
2. Convection: transfer of heat energy in liquids and gases (or fluids) caused by density differences.
[Diagram]
Convection occurs in the atmosphere, oceans and mantle of the Earth
3. Radiation: is the transfer of heat by Electromagnetic (EM) waves.
· EM radiation travels at the “speed of light” (about 186,000 miles / second).
· Can travel through gases, liquids, and some solids.
· Can travel through the vacuum of space.
C. Sunlight is composed of many types of EM Energy (see text p.484 and ESRT p.14)
[diagram]
Electromagnetic spectrum | Flash simulation, Animation, Illustration, Picture, Diagram – eduMedia
2. The greatest intensity of sunlight, at the Earths surface is in the visible wavelengths.
(Text p.675)
[diagram]
B. Factors Affecting Daily Temp. Changes
1. Time of Day:
Warmest time of day is…
the mid-afternoon (around 3:00 PM)
This is when Ground Radiation is greatest.
Greenhouse Effect – animated diagram
[Diagram]
Coldest time of day is …
around sunrise (6: 00 AM)
This is when Ground Radiation is lowest.
[Graph]
2. Cloud Cover
· Clouds block incoming sunlight.
· This makes day time temp. cooler.
· Clouds trap outgoing ground radiation.
· This makes night time temp. warmer.
· Clouds decrease the
Daily Temperature Range.
3. The movement of Cold and Warm
Air Masses has the greatest affect on day to day temp. changes.
(see text p.559-560)
II Air Pressure is the weight of the atmosphere pressing down on the surface.
How come we don’t feel it?
Swimming pool/equalize air pressure
Train to Penn Station
Driving on hilly road
Airplane ascent/descent.
A. Air Pressure is measured using a Barometer (see text p.533).
Average air pressure is about:
29.92 inches of Mercury or
1013.2 millibars (mb.) or
1.0 atmospheres (atm.)
Vidclip- Atmospheres_of_Pressure
B. Conversions- Practice (see ESRT p.13)
1. Each mark on the millibar scale = _____ mb.
2. Each mark on the inches scale = _____ inches
3. 1020 mb. = _____ inches.
4. 1021 mb. = _____ inches.
5. 29.00 inches = _____ mb.
6. 28.88 inches = _____ mb.
C. Factors affecting the Air Pressure
1. Elevation: the greater the altitude the less the air pressure.
(see ESRT p.14)
Practice:
Pressure at Sea level = _____ atm.
Pressure at Tropopause = _____ atm. Pressure at altitude of 15 miles = _____ atm.
Pressure at altitude of 40 km. = _____ atm.
Lower air pressure affects many things:
More difficult to breathe at high altitude.
Vidclip – Air_Density and_the_Effects_on_the_Human_Body
Air less dense, easier to hit a home run.
http://profhorn.meteor.wisc.edu/wxwise/baseball/homerun.html
2. Temperature: Warm air is lighter and lower pressure than cold air.
[Why?- diagram]
3. Humidity: Moist, humid air is lighter and lower pressure than dry air.
[Why?]
Lowest Pressure air is Warm and Moist.
Highest Pressure air is Cold and Dry.
YouTube – Air Pressure – Science Theater 4
Try to sink a basket! Change the air pressure in the ball.
YouTube – Bill Nye the Science Guy – “Smells Like Air Pressure”
III Wind is the movement of air from areas of High Pressure to Low Pressure.
[Diagram]
A. Wind velocity is measured with an
· Anemometer for speed and a
· Wind Vane for direction.
(see text p. 545)
· Wind Direction is always labeled from where it comes from (not going to).
B. Local Winds blow over a small distance and often change direction.
Examples:
· Valley and Mountain Breezes
(text p.544)
· Land and Sea Breezes (text p.543-544)
Observe an animation of land and sea breezes.
YouTube – WeatherBug’s Real World Instruction: Wind
[Diagram]
C. Global Winds blow long distances from the same general direction.
[Set up Diagram]
· In the tropics:
-Heating of the sun warms and moistens air.
-Density decreases and air rises.
-This forms a permanent low pressure zone along the equator.
· Along latitudes 30° N. and 30° S.
-Air cools and dries.
-Density increases and air sinks
-This forms permanent high pressure zones
· Wind then blows from 30° (high pressure) to the equator (low pressure).
· These winds are called the Trade Winds.
· Circular movement of air is called a
Convection Cell.
global wind animation
D. Global Wind direction curves due to the rotation of the Earth. This is called the Coriollis Effect.
[Diagram 2]
(See ESRT p.14)
YouTube – Reference Table p 14 Global Winds.mov
Sailing around the world using Global Winds 1
Sailing around the world using global winds 2
YouTube – global wind visualisation
E. Winds often circulate around centers of High and Low Pressure.
B. In a Low Pressure System or Cyclone, wind circulates counterclockwise and inward towards the center.
Air rises upward in the center.
[Diagram]
B. In a High Pressure System or Anticyclone, wind circulates clockwise and outward from the center.
wind circulation NH
[Diagram]
Centers of High and Low Pressure in the U.S. right now:
National and Local Weather Forecast, Hurricane, Radar and Report
In the Southern Hemisphere, winds circulate the opposite way.
BOM_Air pressure
F. Isobars are isolines of equal air pressure.
[Diagram]
The closer the isobars,
· the faster the pressure is changing,
· the greater the pressure gradient
· the greater the wind speed.
[Reverse statement?]
G. Pressure Gradient can also be calculated.
Use the formula in ESRT- p.1
[Example: Board]
YouTube – Wind.mov
Lab: Wind Patterns
IV Water and the Atmosphere
A. Water exists in three states or phases.
[Diagram- phase changes]
(see text p.505)
B. Water heats up and cools down slowly because it has a high Specific Heat. (see ESRT p.1)
C. The Heating Curve for Water
[Diagram- Graph]
Heating curve for water
Heating curve for water
A – B: Ice absorbs heat. Temp. increases.
B – C: Ice absorbs heat and melts. No
Change in temp.
C – D: Liquid water absorbs heat.
Temp. increases.
D – E: Liquid water absorbs heat and
boils (vaporizes).
No change in temp.
E – F: Water vapor absorbs heat.
Temp. increases.
1. Facts to Know: see ESRT p.1
· Vaporization absorbs heat (2,260 Joules / gram). This cools the environment.
(sweating, dogs panting, wet skin-cold)
· Condensation releases this heat and warms the environment.
(source of heat for hurricanes)
· Melting absorbs heat and cools the the environment (334 joules, gram).
(ice cubes in drink)
· Freezing releases this heat and warms the environment.
D. Water in the air.
1. Humidity is the amount of water vapor
the air contains.
2. Warm air can hold more vapor than cold air. (see text p.506)
Warm air has a greater vapor capacity.
[Diagram]
E. Relative Humidity (RH) is the actual amount of vapor in the air compared to its vapor capacity.
“How full the air is with water vapor.”
YouTube - relative humidity
8(c) Atmospheric Humidity diagram
[diagram]
F. RH increases if;
a. More vapor enters the air by evaporation or transpiration.
b. The temp. decreases.
[demo]
YouTube - Relative Humidity Demo
YouTube - Jeanetta Jones explains about relative humidity
Relative Humidity in your house in Winter- have fun!
G. When RH = 100%, the air is saturated, and condensation may occur.
H. Dew Point is the temp. at which the air becomes saturated with vapor.
The closer the air temp to the Dew Point temp., the higher the RH, and the greater the chance of clouds and condensation.
[Graph]
I. The instrument used to measure Dew Point temp. and RH is the
Sling Psychrometer.
1. It has two thermometers; a Wet Bulb and a Dry Bulb.
2. Water evaporates from the wet bulb and cools it.
3. The wet bulb temp. is always less than or equal to the dry bulb temp.
4. Use the ESRT (p.12) to determine Dew Point temp and RH.
[Examples: on board]
V Clouds and Precipitation
A. Clouds form when air rises, expands, and cools.
(See text p.503, 510, 511)
YouTube - Timelapse of Tucson cloud formations
YouTube - White Clouds Time Lapse
YouTube - Clouds
1. When the air is cooled to the dew point temp., condensation occurs forming clouds.
2. What makes air rise?
http://earthsci.org/processes/weather/weaimages/cldform.gif
· Heating by the sun.
[Diagram]
· Different types of air collide.
[Diagram]
· Air rises up and over mountains.
[Diagram]
3. Conditions necessary for condensation and cloud formation:
· Air Temp. = Dew Point temp.
· Small solid particles called Condensation Nuclei, are present.
(Examples: dust, pollen, sea salt)
· If air is too clean and no nuclei are present, the air may become Supersaturated.
Cloud Seeding can make condensation occur.
YouTube - How Does Cloud Seeding Work?
YouTube - Cloud seeding vid
YouTube - Chinese fight drought with chemical cloud-seeding
B. Types of Clouds:
See text p.518-519, Cumulus text p.515
p.517- cirrus
C. Precipitation occurs when water droplets or ice crystals grow heavy enough to fall to the Earths surface.
http://earthsci.org/processes/weather/weaimages/ccprcess.gif
1. The type of precipitation that falls depends on the temp. of the air at different levels.
Precipitation Type
2. Types of Precipitation
· Rain: all liquid water.
· Snow: Vapor changes directly into ice crystals.
snowflakes - Google Image Search
· Sleet: raindrops freeze while falling to the ground.
· Hail: Ice pellets collide with raindrops and freeze.
Examine an animation of hail forming.
hail - Google Image Search
· Glaze (ice storms): Liquid water freezes on contact with frozen ground.
ice storm - Google Image Search
http://profhorn.meteor.wisc.edu/wxwise/baseball/homerun.html
Hurricane animations
Hurricane Visualizations
Photo of Earths atmosphere
The Earth's Atmosphere