GEOG 207: CLIMATE QUEST
LECTURE 1 -- WHAT DRIVES CLIMATE? WHY DOES CLIMATE VARY FROM PLACE TO PLACE?
Illustrations from Ruddiman, 2001, Earth's Climate, Past and Future
What is Climate?
Basically, Average Weather:
Differences in temperature, precipitation from place to place around the world
Includes concepts in physics, chemistry, biology, geology, geography, math
Includes all aspects of the Earth's Natural System (Five Spheres)
Atmosphere (gaseous envelope around the earth, AIR)
Hydrosphere (all WATER on earth, especially oceans, lakes, vapor)
Cryosphere (all ICE on earth, especially ice sheets, glaciers)
Lithosphere (especially earth's crust -- ROCK, SOIL)
Biosphere (all LIFE on earth -- found in all four spheres)
Basic concepts for understanding climate:
Systems, open and closed
A group of interacting, interrelated, or interdependent elements forming a complex whole
A naturally occurring group of objects or phenomena: the solar system
Includes defined boundaries:
OPEN: matter and /or energy can pass in and out across boundaries
CLOSED: No matter or energy can pass into or out of the systemExamples?
Energy and materials, matter?
Equilibrium – balance between energy income and outgo in a System
Feedback: A process in which a system (commonly ecological or biological) regulates itself by monitoring its own output. That is, it “feeds back” part of its output to itself. Generally, a response to the output of a system.
Positive Feedback:
A form of feedback in a closed loop system in which small changes in the level of output tend to be exaggerated so that deviations from the norm are increasedExamples?
Negative Feedback:
A type offeedback in which the system responds in an opposite direction to the output change.
It is a process of feeding back to the input a part of a system's output, so as to reverse the direction of change of the output.
This tends to keep the output from changing, so it stabilizes the system and tends to maintain constant conditions (equilibrium)Examples?
Albedo:
The amount of solar radiation (sunlight) reflected off of the earth's surface (global albedo), or
The amount of solar radiation reflected off of a surfaceFresh snow: 80-95%
Forest: 10-20%
Grass: 25-30%
Asphalt (black top): 5-10%
Water bodies: 10-60% (depends on Sun's angle)What drives and controls climate?
Solar radiation: primary energy drives all Earth systems
Heat – all matter in universe contains some heat
Differences in heat drive earth’s systems
Heat vs temperature:
Heat -- Total molecular (or atomic) energy in matter
Temperature -- Average molecular energy in matterEARTH'S ENERGY BALANCE
Balance between incoming solar radiation (short wave energy)
and outgoing heat (longwave energy)What happens to sunshine when it enters the Earth's Atmosphere?
What happens to outgoing heat when it leaves the Earth's Surface?
EARTH-SUN RELATIONSHIP
As Earth orbits around the Sun, the point on earth that is directly below the sun migrates between 23.5 degrees North (our summer) and 23.5 degrees South (our winter)
Causes Differences in Temperature (Average Heat) from place to place, and Time to Time (Seasons)
Temperature also Varies with type of surface, Water or Earth
How Humid Is It Where You Live?
Earth's General Atmospheric Circulation
(WINDS and PRESSURE)
REGIONAL EFFECTS OF TOPOGRAPHY -- RAIN SHADOW EFFECT
Ocean Currents Driven by General Winds
Red = Warm; Blue = Cold
Ocean's Conveyor Belt -- Thermohaline Circulation
What causes climate to differ from place to place?
Solar radiation – earth-sun geometry, seasons
Latitude: higher = colder; lower = tropical warm
Seasons: higher latitude, greater seasonality
Atmospheric circulation: large scale winds
Water distribution: oceans, lakes, ocean currents
Land distribution
Water versus land: continentality
Elevation: higher = colder
Ice Sheets, glaciers
Larger = lower sea level (Ice Ages)
Smaller = higher sea level (Global Warming)
Vegetation: influences temperature, humidity, precipitation
