PHSC 4013 Earth Science
Mr. Brian M. Cudnik,
Instructor
26 August 2008
What is Earth Science?
• Earth Science is the Study of the Earth
System as a whole, along with each
component system part and how the parts
interrelate to make up the whole
• Spheres of Earth Science include:
Meteorology, Geology, Oceanography,
Environmental Science, and Astronomy
• These spheres are interrelated and have a
common foundation--Physics
What is Science?
• The Scientific Method and our curiosity
• We live in an age of unprecedented
exploration (some Tools of Exploration
appear on the next page)
• Forms of Science: the Life Sciences and the
Physical Sciences
• Why Mathematics, the Language of
Science, is important?
• Science helps us understand Patterns
The Scientific Method
• The scientific method is our paradigm, our approach
to investigate Nature
• The method begins with a Hypothesis…
• The Hypothesis is tested repeatedly through
observation and experimentation
• If the hypothesis passes the test, it is promoted to a
Theory or a Model
• A scientific Law is a basic principle that describes a
particular type of behavior in nature and is usually
brief in nature, e.g. Newton’s laws of motion
The Interconnectedness of Science
• These branches of science are not isolated,
compartmentalized, but are interconnected (some
examples…)
• We will stress this at times over the course of the
term as we explore various aspects of Earth
Science
• The foundation of science rests largely with
Physics, the science behind the sciences
• The Speed of Light and the Size of the Cosmos…
Natural Systems and Environments
• System = a group of interacting parts that
forms a complex whole (can you think of
some examples in the everyday realm?)
• Environment = everything that surrounds
and influences an organism (what comes to
mind when we mention “environment”?)
• Energy sources that power the Earth system
include external (the Sun) and internal (heat
from the interior of the Earth)
AN EXAMPLE OF A SYSTEM: “THE WEATHER MACHINE”
Solar radiation interacts with Earth’s atmosphere and its energy is
absorbed by water vapor Æ fuels cloud formation and drives
storms.
Earth’s annual motion around the Sun results in the seasonal
weather changes; the weather takes place exclusively in the
lower part of the atmosphere known as the troposphere.
Solar heating Æ heats the ground, which heats the air above it Æ
warmed air rises and is replaced by cooler air Æ warm air aloft
migrates north and cools, then sinks Æ circulation cell is set up
Æ the Earth’s rotation provides the stage for the Coriolis effect
to break up the circulation into three cells per hemisphere Æ
continents further modify the resulting circulation.
The Physics that help us understand
Earth Science I: Gravity
• Gravity: not only keeps us on the ground,
but it holds the Earth together
• Our knowledge of gravity developed over
the centuries through Newton and Kepler
• Gravity is the attractive force between two
objects of mass
• Gravity is the weakest of the four known
forces in Physics
Newton’s Laws of Motion
• Newton’s Laws of Motion form the basis of
classical mechanics
• Did you know his first law of motion was
not his own, but was derived by Galileo?
• The three laws of motion govern all moving
objects: from people to cars to planets to
galaxies.
• These laws of motion are…
Newton’s Law of Universal
Gravitation
• By comparing the motion of the Moon to that of
falling objects on Earth, Sir Isaac Newton concluded
that gravitational forces were responsible for both.
• This law extends gravity beyond the Earth and to the
ends of the Universe.
• The strength of the force directly depends on the
masses of the objects, and also falls as the square of
the distance (that is double the distance, the force
drops by a factor of four)
Some Commonly-Asked
Questions Addressed in Earth
Science: Why is the Sky Blue?
• The sky is blue because of what is termed Rayleigh scattering.
Violet and blue light are scattered much more efficiently than
orange and red light, hence the blue sky
• The makeup of visible light—all colors of the rainbow (briefly
discuss wavelength and energy)
• Refraction and scattering are two ways visible light is spread into
its component colors
• When the sky is really hazy, a process called Mie scattering
causes all wavelengths of solar light to be scattered more
efficiencyÆ the sky is more white
Why the sky is blue, the sunset
red, and twilight multi-colored
• Twilight results from scattering of sunlight in the upper
atmosphere after the sun has set for a particular location. The
length of twilight varies with time of year and latitude.
• Twilight is designated in three stages, based on illumination:
civil, nautical, and astronomical
• If a volcano erupts, sending ash into the stratosphere, that ash
scatters all colors of light equally, resulting in the especially red
sunsets and twilights experienced for as long as one year after the
eruption
Why the sky is blue, the sunset
red, and twilight multi-colored
• Crespuscular rays, consisting of alternating light and dark bands,
appear to diverge in a fanlike patter from the sun’s position from
sunset to up to one half hour after sunset. Just after sunset, if they
are especially bright, they may appear to converge at a point
directly opposite the location of the sun.
• Just after sunset, a dark band is visible on the eastern horizon,
with a pinkish edge. This is the shadow of the earth, projected on
the atmosphere, that appears to rise like a curtain for several
minutes after sunset. The pinkish edge is sometimes referred to by
astronomers as “the belt of Venus”