PHSC 4013 Earth Science

1. PHSC 4013 Earth Science Mr. Brian M. Cudnik, Instructor 26 August 2008

2. 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

3. 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

5. 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

6. 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…

8. 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)

9. AN EXAMPLE OF A SYSTEM: “THE WEATHER MACHINE” Solar radiation interacts with Earth’s atmosphere and its energy is absorbed by water vapor  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  heats the ground, which heats the air above it  warmed air rises and is replaced by cooler air  warm air aloft migrates north and cools, then sinks  circulation cell is set up  the Earth’s rotation provides the stage for the Coriolis effect to break up the circulation into three cells per hemisphere  continents further modify the resulting circulation.

10. 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

11. 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…

12. 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)

13. 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 efficiency the sky is more white

14. 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

15. 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”