Transcript Climate_edit attempt - Rondout Valley Intermediate School

SOME REVIEW…

Weather is the condition in the atmosphere
at a given place and time.

Climate describes the long-term pattern of
weather at a given location.

Weather and climate are key components of
Earth's energy flow and cycles of matter,
especially water, oxygen and carbon
dioxide.
Generally based on
temperature
and moisture patterns
Energy and the atmosphere

Heat energy enters the atmosphere from
heat absorbed and radiated from the
earth, from friction due to winds, volcanic
activity and absorption of insolation.
Radiation

All bodies of matter radiate
electromagnetic energy. The higher the
temperature of the radiating body the more
energy it will emit and the shorter the
wavelength.
Energy can be transferred three ways:

Radiation travels as electromagnetic waves and
can even pass through empty space.

Convection occurs in fluids (liquids and gases) and
involves density-driven currents. Warmer, lessdense fluids rise and cooler, more-dense fluids sink.
Convection currents are most important in creating
weather and moving tectonic plates.

Conduction involves heat energy moving between
substances that are touching, such as your hand
and a hot pot.

The electromagnetic spectrum
describes all of the various types of radiant
energy, each of which covers a specific
range of wavelengths. (ESRT p. 14)

The Sun's energy reaches Earth as
incoming solar radiation (“Insolation”).
Most of the insolation is visible light, with
lesser amounts of infrared (heat) and
ultraviolet waves.
INSOLATION
Incoming
solar
Radi
ation
ABSORBTION OF ENERGY:

Dark-colored objects are good absorbers
and radiators of heat, and poor reflectors.

Light-colored objects are good reflectors,
but poor absorbers or radiators.

Smooth surfaces are good reflectors and
rough surfaces are good absorbers.
Energy & Temperature:

Kinetic energy is energy of moving things.
The faster they move, the more KE they use.

Temperature is the "average kinetic energy"
of an object.

Potential energy is stored energy. It
increases with mass and as the object gets
higher.
ALBEDO

The amount of insolation reaching Earth is
balanced by the amount reflected back to
space (albedo) and the terrestrial reradiation, mostly as infrared waves.

Radiative balance (equilibrium) occur
when the energy emitted by an object is
equal to that absorbed by the object.
Global and Regional Weather
and Climate Systems

Local weather is a small part of global and
regional weather patterns.

Global wind, pressure, and precipitation
patterns result from differences in the
amount of energy received at different
latitudes and Earth's rotation.

Global climate patterns (ESRT p. 14) include:
wet conditions and calm winds centered
around the equator (doldrums); east-to-west
winds trade winds in the tropics; zones of
calm centered around 30 degrees north and
south ("horse latitudes"); west-to-east winds
in the mid-latitudes ("prevailing westerly");
and east-to-west winds at high latitudes
("polar easterlies").
Additional Climate and Weather Factors

Adiabatic Cooling: As air rises, it cools because it
expands and the pressure decreases.

Adiabatic Heating: As air sinks, it warms as it
contracts and the pressure increases.

Orographic effect: As air rises up the windward
side of a mountain, adiabatic cooling occurs, and as
it sinks down the leeward side, adiabatic warming
occurs. So the windward side has greater cloud
cover and precipitation, and the leeward side often
has a rain-shadow desert.
Water & Climate:

Water has a higher specific heat value
than rocks, so when the same amount of
insolation strikes materials at a shoreline,
the water will remain cooler and the beach
will warm up more rapidly.

These heating rate differences produce
on-shore sea breezes during the day and
off-shore land breezes at night.
WARM AIR RISES
COOL AIR
MOVES
INLAND
COOL AIR
OVER THE
LAND PUSHES
OUT TO SEA
WARM AIR RISES

Large bodies of water make cooler
summers and warmer winters.

On a regional scale, similar factors create
the monsoons, with wet-seasons in
summer and dry-seasons in winter.
A long term perspective
Global Warming…Truth?
Fiction? Both?
CO2 levels in the atmosphere rising
 Average global temperature is rising
 Polar ice caps and mountain glaciers
are shrinking
 Sea level is rising
 Deserts are expanding
 Weather is getting more severe

Is this normal?

How can we tell if the present change in
climate is normal or something produced
by humans?

Is the amount of present climate change
normal or is it extreme?

Is there any way to answer these
questions?
Changing Perspectives

Our perspective: single human life.

We can expand to a few other generations
based on research.

We need a longer time frame to evaluate
global climate change.

So…how do we do that???
The Geologic Record

The evidence contained in the ROCKS of the
EARTH for the past 4.6 BILLION years
Provides us with longer perspective
 Contains indirect evidence of climate
 Contains direct evidence of climate
 Gives us a history of global climate change
on a scale of millions of years to billions of
years.

Indirect Evidence

Evidence for
Aridity
 Warm Climate
 Cold Climate


Recorded by specific types of rocks
Examples: Desert sandstones
Examples: Reef Limestones
Examples: Glacial Features
Direct Evidence

Ice Cores – a core sample from glaciers
that have trapped air bubbles from
previous time periods


Can contain wind-blown dust, ash, bubbles of
atmospheric gas and radioactive substances
Sediment Cores - long cylinders of
sediment taken from beneath the surface
of the (usually) ocean floor.
Ice Cores
Data from Ice Cores

Direct Evidence for last 100,000 years

Quantities of dust in each layer


Related to wet vs. dry climate
Air bubbles trapped in each layer
Samples of ancient air
 Levels of CO2

Sediment Cores
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
Deep Sea Drilling Project (DSDP)
Ocean Drilling Project (ODP)
Integrated Ocean Drilling Project (IODP)
Coring in lakes and bogs
contain microscopic fossils of marine animals,
volcanic glass, sands originally from land cosmic
material, and other unusual materials unique to
a marine environment

The microfossils are important as time and
environmental indicators; they are very sensitive to
slight changes in temperature and chemical changes
in their environment.

Volcanic glass is an important "time marker" and
records instantaneous geological events.

Sands can indicate the presence of ocean currents,
tell of ancient shorelines, reveal a past dust storm, or
record submarine slides which might indicate
submarine earthquakes.

Deep-sea samples hold a permanent record of
magnetic history revealing to scientists the everchanging magnetic orientation of the poles.
So…What does the
Geologic Record Tell Us?

The “normal” climate of the past 1.0 billion
years was…
Warmer than present
 More uniform than present (less fluctuation)


Past 20 million years have been highly
variable and generally much colder
Climate History:
20 Ma to Present

20 Ma – climate was somewhat moderate

Similar to present

5 Ma – coldest climate of past 65 million years

2 Ma – Great Ice Ages begin


At least 4 episodes of glacial advance & melt back
12,000 – 10,000 Modern Climate sets in
Recent Climate History

7000-6000 BP - Warm Peak

950-1300’s – Medieval Warm Spell

1300’s – Cool and Wet

1550 – 1850 – “Little Ice Age”
Food For Thought

How many of the great events of recorded
human history have been directly
influenced by climate?
Recent Climate History

7000-6000 BP - Warm Peak – Great Ancient
civilizations (e.g., Mesopotamia, Egypt)

950-1300’s – Medieval Warm Spell – Rise of “modern”
European nation-states

1300’s – Cool and Wet – Bubonic Plague/Dark Ages

1550 – 1850 – “Little Ice Age”
 First Settlers come to America – many deaths
 Washington crosses the Delaware
 Winter at Valley Forge
So, are we to blame?

Paleoclimatic record reveals major shifts in
climate through time

Is it coincidence or causation that climate is
warming as we come out of last ice age?

Is it coincidence or causation that industrial
revolution falls within this same time?
What factors cause changes in climate?

Long term vs. short term changes

Volcanic eruptions
Ex: eruption of Krakatau in 1883
 Yellowstone supervolcano – 2 MYA, 1.3
MYA, & 630,000 YA

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Earth’s orbital variations