The Earth as a System

A View of Earth Scientists and others are beginning to view the Earth as a system of interconnected spheres, not a collection of unrelated parts.

The Earth is unique in the Solar System; it is the only planet that can support life. Earth is able to do this by the interactions of four spheres: Atmosphere, Geosphere, Hydrosphere, and Biosphere.

The Atmosphere The

ATMOSPHERE Features: gaseous envelope that surrounds the Earth, composed of gases that help sustain life 78% N, 21% O, 1% CO2 other gases absorb and alter rays from the sun only one in the solar system that has oxygen

Atmosphere cont’d Functions: 1. Insulates the Earth CO2 in the upper atmosphere allows light from Sun to reach Earth, heating it up reflects heat radiating from Earth back to the surface (keeps it from going into space) greenhouse effect

Atmosphere cont’d 2. Protects the Earth- a layer of special oxygen (ozone) keeps out most of the Sun’s harmful UV rays. CFC’s destroy ozone.

The Lithosphere (Geosphere)

Lithosphere/Geosphere Solid rocky surface of the Earth A. Features: 1. covered with sediments-rock particles broken down by erosion 2. geologically active---earthquakes, volcanoes, mtn. building due to plates moving and interacting

Lithosphere/Geosphere cont’d. B. Functions 1. breaks down rock to provide minerals for soil that make plant life possible 2. provides habitat (swamps, deserts, prairie, etc.) for tremendously diverse life forms

The Hydrosphere

Hydrosphere Features: layer of water found on, under, and over the surface of a planet covers 70% of Earth’s surface Functions: Earth’s surface T’s and P’s allow H20 to exist in all 3 states Water on Earth is always in motion---continually RECYCLED!

BIOSPHERE Features: All living things on the Earth compose the biosphere Functions: interactions between biosphere and the other three spheres gave rise to the conditions that support life

Four Spheres Four spheres of the Earth System are constantly moving, changing and interacting. These actions do not occur in isolation!

Interactions Cause Changes in the Spheres Interactions can take many forms: single events like a volcano or tornado temporary events, such as a heat wave or cold wave ongoing, such as erosion

What is a System? A part of the universe that can be studied separately that includes time as a variable. Open system- the surroundings freely exchange energy and matter Closed system-energy may enter, but matter doesn’t enter or leave

Law of Thermodynamics 1st law states energy can neither be created nor destroyed 2nd law states that when energy changes, it is converted from a more useful, more concentrated form to a less useful, less concentrated form. This means that energy can never be completely recycled!!!

Energy Flows, Matter Cycles

Open Systems All of the "spheres" of the Earth system are considered to be OPEN systems because energy and mass are exchanged between them.

Open System Example- The Oceans & Atmosphere ocean surface represents the interface between the hydrosphere and the atmosphere Solar radiation passes through the atmosphere and is absorbed by the ocean. The absorbed energy evaporates water from the ocean As the water vapor (mass) enters the atmosphere it carries with it the heat used to evaporate the water Energy AND mass are exchanged!

Earth as an Open System The functioning of our planet relies on a constant INPUT of energy from the Sun. SOME of this energy leaves Earth in the form of heat flowing out to space. Earth is an open system with respect to energy.

Closed Systems Extremely rare in nature No natural closed systems exist on Earth, but the planet itself can be thought of as an “essentially” closed system.

Is the Earth an Open or a Closed System? The Earth system as a whole is a closed system. Boundary is outer edge of atmosphere. HOW IS IT CLOSED?

Earth as a Closed System Earth is a recycling planet! All the matter on Earth has been here since the planet was formed. We don't get new matter; old matter does not go away into outer space. The same matter keeps getting used over and over again. Earth is essentially a closed system in terms of matter.

So is the Earth A Closed or Open System??? The seemingly simple question of whether Earth is an open or closed system, like many other questions in science, cannot be answered ‘yes’ or ‘no’ without qualification! However, we usually say CLOSED!