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 system

Examples?

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 increased

Examples?

Negative Feedback:
A type of feedback 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 surface

Fresh 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 matter

EARTH'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