Senior 2

Introduction  If we are going to understand the weather, we first have to understand a little bit about the earth.  We need to know where weather comes from, and what affects the type of weather we experience.  We know a lot about weather through centuries of observation and experimentation.  We didn’t always know quite so much...

Weather over time  Historically, many cultures believed that the weather was controlled by the Gods.  Different weather conditions were explained by the mood of the Gods.  People would pray to the Gods for good weather and even make sacrifices.  They never really had very good luck!

Modern view of the weather  As you know, the earth is shaped like a ball or sphere. If you looked at the earth from a spaceship, you would see that most of it looks blue. This is the blue of the hydrosphere, the part of the earth made of water. Water covers almost three quarters of the earth’s surface.  You would also see the greens and browns of the land areas of the earth. The land is part of the lithosphere, the portion of the earth made of rock.  There is another part of the earth that you cannot see. The atmosphere is the thin layer of gas that surrounds the earth.

The Lithosphere  The land areas of the earth.  Large areas = continents  Smaller areas = islands

The Hydrosphere  The part of the earth that is covered by water (75%)  Largest part is the oceans made up of salt water.  Smaller part is rivers,lakes and glaciers.

The Atmosphere  The part of the earth that is made up of gases.  78%Nitrogen  21% Oxygen  Also CO 2, Neon, Argon and water vapor  Why are these gases important to us?

They support life on earth!  Nitrogen- An important plant nutrient.  Oxygen- Important for animals to breathe. (cellular respiration)  CO 2- Necessary for photosynthesis.

Let’s make a pie chart for our notes. MMMMM Pie Chart!!! O 2 = 21% N 2 = 78% Trace gas 1%