BIG Idea: • The composition, structure, and properties of Earth’s atmosphere form the basis of Earth’s weather and climate.
Who studies atmospheric conditions? • Meteorologists…that’s who!
I. Characteristics of the Atmosphere • Weather = day-to-day changes inatmospheric conditions. • These conditions include: • Temperature • Air movements • Moisture content
Climate = general weather conditions averaged over many(about 30) years
A. Composition of the Atmosphere • 78% Nitrogen • 21% Oxygen • 0.9% Argon • 0.1% Other
Ozone – protects us from harmful UV (ultraviolet) rays Damaged by CFCs (poisons in ACs and refrigerators) Ozzy Ozone
Have you noticed the weather today? How would you describe it?
B. Properties of the Atmosphere • Temperature • Air Pressure • Humidity
1. Temperature • measure of the average kinetic energy of particles in a material • more energy = moving faster = higher temperature • measured with a thermometer
2. Atmospheric (Air) Pressure • the ratio of the force of the air to the area of the surface on which it presses • the weight of the atmosphere pressing down on Earth’s surface
BAROMETER • an instrument that measures atmospheric pressure
b. Aneroid Barometer • Aneroid = ‘without liquid’
3. Humidity • the amount of water vapor in the atmosphere at a given location on Earth’s surface
C. Layers of the Atmosphere • Based on temperature differences, scientists identify four layers of Earth’s atmosphere • Each layer is separated by a “pause”
1. Troposphere: all weather occurs here • Layer closest to Earth’s surface
3. Mesosphere: coldest layer (-90°C )4. Thermosphere: hottest layer (over 2000°C); nitrogen and oxygen atoms absorb solar energy
II. Solar Energy A. Radiation: all forms of energy that travel through space as waves
Why does the inside of a closed parked car heat up, while the windows stay cool?
B. Greenhouse Effect: atmosphere traps (long) infrared rays • The Sun’s energy is trapped inside.
What are the ‘greenhouse gases’ that trap heat within our atmosphere?
Water vapor Carbon dioxide produced by humans burning of fossil fuels (oil, gas, coal)
Convection: transfer of heat energy in gases or liquids due to density differences.
2. Conduction: transfer of heat energy through matter from particle to particle; most effective in solids.
3. Radiation: waves that directly transport energy through space; brings HEAT to our planet.
III. Winds Created by uneven heat distribution at Earth’s surface The amount of energy reaching any given point on Earth’s surface is controlled by the angle of sunlight striking the surface
Our tilt! Where on Earth will you receive more of the sun’s energy per unit area? Where will you receive less?