Foundations of Earth Science - Columbia Southern …© 2014 Pearson Education, Inc. Heating the Atmosphere Chapter 11 Lecture Outline Natalie Bursztyn Utah State University Foundations

© 2014 Pearson Education, Inc.

Heating the Atmosphere

Chapter 11 Lecture Outline

Natalie BursztynUtah State University

Foundations of Earth ScienceSeventh Edition


Focus Question 11.1

Distinguish between weather and climate.


Focus on the Atmosphere

• Weather – Occurs over a short period of time – Constantly changing

• Climate– Averaged over a long period of time – Generalized, composite of weather



• Elements of weather and climate – Properties that are measured regularly:

• Temperature• Humidity• Cloudiness• Precipitation• Air pressure• Wind speed and direction




Focus Question 11.1

Distinguish between weather and climate.– Weather

• Occurs over a short period of time • Constantly changing

– Climate• Averaged over a long period of time • Composite of weather


Focus Question 11.2

• What is ozone? Why is ozone important to life on Earth?


Composition of the Atmosphere

• Air is a mixture of discrete gases• Major components of clean, dry air

– 78% Nitrogen (N)– 21% Oxygen (O2)– Argon and other gases – 0.036% Carbon dioxide (CO2)





Variable components of air • Water vapor

– Up to 4% of air’s volume– Forms clouds and precipitation– Greenhouse gas

• Aerosols– Tiny solid and liquid particles – Water vapor can condense on solids– Reflect sunlight– Color sunrise and sunset





• Variable components of air – Ozone

• Three atoms of oxygen (O3)• Distribution not uniform • Concentrated between 10 and 50 km above the surface • Absorbs harmful UV radiation • Human activity is depleting ozone by adding • Chlorofluorocarbons (CFCs)




Focus Question 11.2

• What is ozone? Why is ozone important to life on Earth?

– Three atoms of oxygen (O3)– Absorbs harmful UV radiation that negatively impacts life on

Earth


Focus Question 11.3

• What is the environmental lapse rate, and how is it determined?


Vertical Structure of the Atmosphere

• Atmospheric pressure is the weight of the air above. • Average sea level pressure is 1000 millibars or 14.7

psi • Pressure decreases with altitude

– Half of atmosphere is below 3.5 mi (5.6 km) – 90% of atmosphere is below 10 mi (16 km)





• Atmospheric layers based on temperature • Troposphere

– Bottom layer– Temperature decreases with altitude– Environmental lapse rate

• Average 6.5˚C per km or 3.5˚F per 1000 feet– Thickness varies

• Average height is about 12 km– Outer boundary is the tropopause





The environmental lapse rate is variable• Actual environmental lapse rate for any particular time

and place• Measured with a radiosonde• Attached to a balloon and transmits data by radio





• Stratosphere– 12 to 50 km– Temperature increases at top– Outer boundary is the stratopause

• Mesosphere – 50 to 80 km– Temperature decreases– Outer boundary is the mesopause

• Thermosphere– No well-defined upper limit– Fraction of atmosphere’s mass – Gases moving at high speeds




Focus Question 11.3

• What is the environmental lapse rate, and how is it determined?˗ The environmental lapse rate is the temperature

decrease in the troposphere ˗ It is determined by measurement with a radiosonde


Focus Question 11.4

• Briefly explain the primary cause of the seasons.


Earth–Sun Relationships

• Earth motions • Rotates on its axis• Revolves around the Sun

• Seasons• Result of:

– Changing Sun angle – Changing length of daylight





• Seasons• Caused by Earth’s changing orientation to the Sun

– Axis is inclined 23.5º– Axis is always pointed in the same direction



• Special days (Northern Hemisphere) – Summer solstice: June 21–22

• Sun’s vertical rays located at Tropic of Cancer• 23.5º N latitude

– Winter solstice: December 21–22 • Sun’s vertical rays located at Tropic of Capricorn• 23.5º S latitude

– Autumnal equinox: September 22–23• Sun’s vertical rays located at equator (0º latitude)

– Spring equinox: March 21–22• Sun’s vertical rays located at equator (0º latitude)




Focus Question 11.4

• Briefly explain the primary cause of the seasons.• Earth’s changing orientation to the Sun

– Changing Sun angle – Changing length of daylight


Focus Question 11.5

• Distinguish between heat and temperature.


Energy, Heat, and Temperature

• Heat is synonymous with thermal energy• Temperature refers to the intensity, or degree of

"hotness"• Heat is always transferred from warmer to cooler

objects • Mechanisms of heat transfer

– Conduction • Molecular activity

– Convection • Mass movement within a substance

– Radiation (electromagnetic radiation)• Gamma waves, X-rays • Ultraviolet,visible, infrared• Microwaves and radio waves





Laws of Radiation 1. All objects emit radiant energy2. Hotter objects radiate more total energy per unit

area than colder objects3. Hotter objects radiate more short-wavelength

radiation than cooler objects4. Good absorbers of radiation are good emitters as

well




Focus Question 11.5

• Distinguish between heat and temperature.– Heat refers to the quantity of energy present– Temperature is the degree of “hotness”


Focus Question 11.6

• What factors cause albedo to vary from time to time and from place to place?



• Incoming solar radiation – Atmosphere is largely transparent to incoming solar

radiation – Atmospheric effects

• Reflection– Albedo (percent reflected)

• Scattering• Absorption

– Most visible radiation reaches the surface – About 50% absorbed at Earth’s surface









• Radiation from Earth’s surface – Earth re-radiates longer wavelengths– Terrestrial radiation– Terrestrial radiation is absorbed by

• Carbon dioxide and water vapor • Lower atmosphere is heated from Earth’s surface

– Heating of the atmosphere is termed the greenhouse effect




Focus Question 11.6

• What factors cause albedo to vary from time to time and from place to place?˗ Amount of cloud cover and particulate matter˗ Angle of the Sun’s rays˗ Nature of Earth’s surface


Focus Question 11.7

• Why has the CO2 level of the atmosphere been increasing for the past 200 years?


Human Impact on Global Climate

• CO2 levels are rising– Industrialization of the past 200 years– Burning fossil fuels

• coal, natural gas, and petroleum– Deforestation

• Present CO2 level is 30% higher than its highest level over the past 650,000 years








Focus Question 11.7

• Why has the CO2 level of the atmosphere been increasing for the past 200 years?– Industrialization – Burning fossil fuels

• coal, natural gas, and petroleum– Deforestation


Human Impact?

• How might the current climate change situation be different if humans had developed the steam engine instead of the gasoline engine?


For the Record: Air Temperature Data

• Temperature measurement– Daily maximum and minimum– Other measurements

• Daily mean temperature • Daily range• Monthly mean• Annual mean• Annual temperature range



• Isotherms used to examine distribution of air temperatures over large areas– Line that connects points of the same temperature – iso = equal, therm = temperature




Focus Question 11.9

• How can cloud cover influence the maximum temperature on an overcast day?


Why Temperatures Vary: The Controls of Temperature• Receipt of solar radiation • Other important controls

– Differential heating of land and water • Land heats more rapidly than water • Land gets hotter than water• Land cools faster than water • Land gets cooler than water


Why Temperatures Vary: The Controls of Temperature



• Other important controls – Altitude– Geographic position– Cloud cover– Albedo




Focus Question 11.9

• How can cloud cover influence the maximum temperature on an overcast day?– Clouds reflect a significant portion of sunlight– Reducing amount of incoming solar radiation– Daytime temperatures will be lower


World Distribution of Temperature

• Temperature maps – Temperatures are adjusted to sea level – January and July used for analysis

• Represent temperature extremes



• Global temperature patterns – Temperature decreases poleward from tropics – Isotherms exhibit latitudinal shift with seasons – Warmest and coldest over land





• Global temperature patterns – Southern Hemisphere

• Isotherms are straighter • Isotherms are more stable

– Isotherms show ocean currents – Annual temperature range

• Small near equator • Increases with an increase in latitude • Greatest over continental locations

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Foundations of Earth Science - Columbia Southern …© 2014 Pearson Education, Inc. Heating the Atmosphere Chapter 11 Lecture Outline Natalie Bursztyn Utah State University Foundations