Long Term and Short Term Changes in Climate; The Albedo Effect.
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Transcript of Long Term and Short Term Changes in Climate; The Albedo Effect.
Long Term and Short Term Changes in Climate; The Albedo Effect
Long Term Climate ChangeThe Cause and Effects
What and How? Long term climate change occurs over
million of years.
There are many causes to L.T.C. changes, such as changes in earth’s orbit, shifting of continents, and cycle of climate change
Climate Change
Continental Drift The movement of continents.
A long time ago, there was a single continent.
Over millions of years, the continent “broke apart” to form present day Earth.
Climate Change
Continental Drift Movement of land affects the climate in
different ways.
Changes in ocean currents, wind patterns and land mass.
The result: heat transfer is affected.
Climate Change
Continental Drift.The Animation.
Cycles Not every type of climate change is
permanent.
Some occur in cycles.
Changes in Earths orbit also causes changes in climate and it occurs in cycles.
Changes in Orbit Specific term: Eccentricity
The Earth’s orbit around the sun changes shape.
It changes after around 100 000 years.
The reason: Jupiter and Saturn’s gravitational pull.
Causes of long term climate change
Changes in Orbit When the orbit changes, Earths distance
from the sun is either consistent or varied.
When the distance is consistent, the seasons are mild.
When The distance is varied, the climate tends to be more “extreme”.
Causes of long term climate change
Changes in Orbit Change in orbit is a
slow transition from almost circular to elliptical.
The change is very slow!
Right now earths orbit is elliptical.
Causes of long term climate change
Tilt The earth slowly
tilts back and forth on its axis.
The earth tilts around 22.1º to 24.5º.
Happens over 41000 years.
Currently, earth is tilted 23.5º.
This angle is decreasing.
Causes of long term climate change
Tilt As the tilt increases, the so does the
difference in temperature of seasons. The Earth also “wobbles” around its
axis.
Climate Change
SHORT TERM CLIMATE CHANGE
Short Term Factors
Volcanic eruptions Changes in the Sun’s radiation Changes in air currents Changes in ocean currents
Volcanic Eruptions
Rocks, dust and gases are released into the atmosphere
The sulfur dioxide particles which are released reflect the Sun’s energy back to space
Since there is less energy, the Earth cools down temporarily
Volcanic Eruptions
Example on pg. 351 (Fig. 7)
Air and Ocean Currents
Changes in thermohaline circulation can cause changes in climate
Thermohaline circulation is the flow of water around the world’s oceans driven by differences in temperature and salinity
There are some changes which occur regularly, an example is El Nino
Ocean Currents
(cont.)
Ocean currents affect climate
Example: The air above warm ocean currents is heated. The land is warmed and rain is produced when this warm, moist air reaches land.
This is why air and ocean currents can affect climate
El Nino
Occurs every 3 to 7 years Prevailing winds temporarily change
direction Ocean currents change Warm water is pushed towards S.
America Because of this, the west coast of S.
America gets warm, wet weather
El Nino
On pg. 353 (Fig. 8) in textbook
The Sun’s Radiation
The amount of radiation the earth receives affects climate
Small changes can affect the climate of the earth
When the amount of radiation is lower, there is less energy, the climate cools
If radiation increases, there is more energy, the climate warms
The Albedo Effect
Feedback Loops
Small changes can have large effects
This is because the small changes can be made bigger because of feedback loops
A positive feedback loop increases the original cause
A negative feedback loop decreases the original cause
Water Vapour and Feedback Loops
An example of positive feedback loops is the water vapour in the atmosphere
More water vapour forms since if the climate warms. Water vapour is a greenhouse gas and traps radiation. This further warms up the earth.
It is the same when the climate cools. Less water vapour is formed and the climate cools even more
Albedo
This is the radiation which is reflected by a surface
Different surfaces have different albedos, an example would be ice which reflects much of the sun’s radiation
The albedo of a planet is a measure of how much radiation is reflected back when the sun shines on it
Earth has an albedo of 0.30-0.40
Albedo Diagram
Albedo Effect
This is an important feedback loop in Earth’s climate
It is a positive feedback loop Relationship between ice on surface of
the Earth and the avg. temperature If the temperature increases, ice melts
and less radiation is reflected which further increases the temperature
If it decreases, ice forms and more radiation is reflected
The Albedo Effect
Questions
1. What are the long term changes affecting the earth?
2. What is continental drift?3. What can the movement of large land
masses cause?4. Does the orbit of the earth change? How?5. What are the short term changes which
can affect climate?6. How do volcanic eruptions cause changes
in climate?
Questions (cont.)
7. What is albedo?8. What is the albedo effect?9. What happens if the temperature of
the planet increases?10.What happens if the teperature of
the planet decreases?
