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© 2017 Pearson Education, Inc.

Heating the

Atmosphere

Chapter 11 Lecture

Natalie Bursztyn

Utah State University

Foundations of

Earth ScienceEighth Edition


• Distinguish between weather and climate.

• Name the basic elements of weather and climate.

Focus Questions 11.1


• Weather

– Occurs over a short period of time

– Constantly changing

• Climate

– Averaged over a long period of time

– Generalized, composite of weather

Focus on the Atmosphere


• Elements of weather and climate

– Properties that are measured regularly:

• Air temperature

• Humidity

• Type and amount of cloudiness

• Type and amount of precipitation

• Air pressure

• Wind speed and direction

Weather and Climate


Weather and Climate


• List the major gases composing Earth’s

atmosphere.

• Identify the components that are most important

to understanding weather and climate.



• Air is a mixture of discrete gases

• Major components of clean, dry air

– 78% Nitrogen (N)

– 21% Oxygen (O2)

– Argon and other gases

– 0.04% Carbon dioxide (CO2)

Composition of the Atmosphere


Major Components


• 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


Variable Components


• Ozone

– Three atoms of oxygen (O3)

– Distribution not uniform

– Concentrated between 10 and 50 km above the surface

– Absorbs harmful UV radiation

Variable Components


• Interpret a graph that shows changes in air

pressure from Earth’s surface to the top of the

atmosphere.

• Sketch and label a graph that shows atmospheric

levels based on temperature.



• 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)

Pressure Changes


Pressure Changes


• Four atmospheric layers based on temperature

– Troposphere

• Lowermost layer

• Temperature decreases with increasing altitude

• Environmental lapse rate

– Average 6.5C per km or 3.5F per 1000 feet

• Thickness varies

– Average height is about 12 km

• Outer boundary is the tropopause

Temperature Changes


Temperature Changes


• 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

Temperature Changes


Temperature Changes


• 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

Temperature Changes


Temperature Changes


• Explain what causes the Sun angle and length of

daylight to change during the year.

• Describe how these changes produce the

seasons.



• Earth’s motions

– Rotation on its axis

• Once every 24 hours

• Circle of illumination is the line separating Earth’s

lighted half from dark half

– Orbital motion around the Sun

• Seasons

– Result of:

• Changing Sun angle

• Changing length of daylight

Earth–Sun Relationships


• 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)




[insert Figure 11.15 and Table 11.1 here]


• Distinguish between heat and temperature.

• List and describe the three mechanisms of heat

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

Energy, Heat, and Temperature


• 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

– All objects emit radiant energy

– Hotter objects radiate more total energy per unit

area than colder objects

– Hotter objects radiate more short-wavelength radiation

than cooler objects

– Good absorbers of radiation are good emitters as well



• Sketch and label a diagram that shows the paths

taken by incoming solar radiation.

• Summarize the greenhouse effect.



• 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

Heating the Atmosphere


• 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



• Summarize the nature and cause of the

atmosphere’s changing composition since

around 1750.

• Describe the atmosphere’s response and some

possible future consequences.



• 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 at least the past 800,000 years

Human Impact on Global Climate


• Important impacts of human-induced global

warming:

– Rise in sea level

– Shift in large-storm paths

• Changes in precipitation distribution

• Changes in occurrence of severe weather

– Stronger tropical storms

– Increasing frequency and intensity of heat waves and

droughts

• Gradual environmental shifts



• Calculate five commonly used types of

temperature data.

• Interpret a map that depicts temperature data

using isotherms.



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

– Easy to visualize temperature gradient



• Discuss the principal controls of temperature.

• Use examples to describe their effects.



• Temperature control – any factor that causes

temperature to vary from place to place and from

time to time

– Receipt of solar radiation

– 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


• Specific heat is the

amount of energy

needed to raise the

temperature of 1 gram

of a substance

1 degree Celsius


of Temperature



of Temperature


• Other important controls

– Altitude

– Geographic position

– Cloud cover

– Albedo


of Temperature



of Temperature


• Interpret the patterns depicted on world maps of January and July temperatures.

Focus Question 11.10


• Temperature maps

– Temperatures are adjusted to sea level

– January and July used for analysis

• Represent temperature extremes

World Distribution of Temperature


• 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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