The Structure of the Atmosphere

QQ1 – What is the function of the atmosphere QQ1 – What is the function of the atmosphere? QQ2 – What is the structure of the atmosphere?

The Function of the Atmosphere A. Earth’s atmosphere allows for life to exist by: Regulating temperature Providing protection from harmful solar radiation Providing space for water and nutrient cycles The Composition of the Atmosphere 78% Nitrogen Gas 21% Oxygen Gas (O2) 1% other-- water vapor, carbon dioxide, argon, helium, hydrogen, ozone, particles (dust, soot), chlorofluorocarbons, etc. CO2 and H2O vapor play a critical role in regulating the amount of heat energy the atmosphere absorbs. Carbon Molecule

The Structure of the Atmosphere A. In order from the bottom up: Troposphere Stratosphere Mesosphere Thermosphere Exosphere *The Sun Makes Thermal Energy! Figure 11.2

Characteristics of the Troposphere Contains most of the atmospheric mass. Weather occurs in this layer. Pollution and smog collect in this layer. Temperature decreases as altitude increases. The amount of heat absorbing molecules (CO2, H2O) decrease as the distance from Earth’s surface increases. The layer closest to the Earth’s surface. Bottom boundary: 0 km (sea level) Top boundary: 10 km, varying from equator to poles Approximate Thickness: 10 km

C. Characteristics of the Stratosphere Contains ozone gas (O3) , making the ‘Ozone Layer’. Jet planes fly here because of steady weather conditions. Temperature increases as altitude increases. Ozone gas absorbs ultraviolet radiation from the sun. Bottom boundary: 10 km Top boundary: 50 km Approximate Thickness: 40 km

C. Characteristics of the Mesosphere Air molecules are less concentrated in this layer. Temperature decreases as altitude increases. With the absence of ozone, temperature again decreases as the number of heat absorbing molecules decrease. Bottom boundary: 50 km Top boundary: 100 km Approximate Thickness: 50 km

Characteristics of the Thermosphere Gas molecules are sparse and widely spaced. Temperature increases as altitude increases. Molecules are heated faster because they are closer to the sun and absorb intense solar radiation. Temperatures are high (up to 1000 °C!), Bottom boundary: 100 km Top boundary: 500 km Approximate Thickness: 400 km

Characteristics of the Ionosphere (part of the thermosphere) This layer is made of electrically charged particles called ions. At the poles, ions interact with air molecules to form auroras. Radio waves from earth reflect off the ionosphere back to Earth. Ranges from 65 km -500 km above sea level.

Characteristics of the Exosphere Air molecules are very sparse in this layer. Only light gases (Helium & Hydrogen) are found here. Temperature increases as altitude increases. Temperatures are high Bottom boundary: 500 km Top boundary: ??? There is no clear distinction between the top boundary and outer space.

Summary Diagram

QQ 3 – What are the layers of the atmosphere QQ 3 – What are the layers of the atmosphere? QQ4 – Create a graph of the layers of the atmosphere demonstrate variation in temperature