Energy in the Earth s Atmosphere Unit Essential Question: What are the different features of the atmosphere that characterize our weather. How does the atmosphere influence life and how does life influence the atmosphere? Presentation Objectives: Identify and describe the three main methods of heat transfer. Differentiate between the radiation produced by the Sun and the Earth. Define temperature and explain how it is measured. Describe the three temperature scales and how to convert between them. Explain how to calculate the mean temperature and temperature range. Differentiate heat from temperature. Define the term greenhouse effect. Explain the importance of the greenhouse effect and how it works. Very Dynamic! The atmosphere is always changing, and these changes require energy to occur. Where does the Earth get its energy from? The Sun! The sun and Earth are separated by a distance of 3,000,000 miles. Q1 How Does it Get Here? Radiation The transfer of energy through space by electromagnetic waves. Q2 All Objects Radiate Energy! All objects produce a mixture of wavelengths. One wavelength is more dominant than the others and is known as the peak wavelength. Depends on temperature. Q3 Wien s Displacement Law Using this law, we know that the... Sun emits short-wave radiation. Earth emits long-wave radiation. The higher the temperature, the shorter the wavelength!
What happens to this radiation? Incoming solar radiation is known as insolation. Q4 What Absorbs and What Reflects? Q The reflectivity of a surface is described by its albedo. 0 = Perfect Absorber 1 = Perfect Reflector Global Albedo Warming The Earth! The insolation absorbed by the Earth increases the Earth s temperature. The Earth then radiates energy as infrared radiation. Q6
Warming The Atmosphere! The energy radiated by the Earth is transferred to the atmosphere. The atmosphere is warmed by the Earth not the sun. Earth s surface warms the lower troposphere by conduction. Process during which heat energy is transferred by direct contact. Q7 Distributing the Energy Once the lower troposphere is heated, it can move the energy to the upper troposphere through convection. Convection is the transfer of energy in a fluid because density differences. Convecting air leads to the formation of clouds and precipitation. Q8 It s All About Heat! Conduction and convection are methods of heat transfer. Heat is the measure of the amount of energy transferred from one object to another because of a temperature difference. Heat flows High Temp Cold Temp Q Heat vs. Temperature When energy is absorbed, the object s temperature changes. Temperature is a measurement of average kinetic energy of the particles that make up an object. Faster molecules = More KE = High Temperature Q10 The thermosphere can have a temperature as high as 100 C, but if you were there, you would freeze. Staying warm is dependent on heat not temperature! Heat = Total Energy Transferred Temperature = Average Energy
Measuring Temperature A thermometer is placed into a substance with a different temperature. Heat is transferred until the thermometer and the substance are the same temperature. Many other properties of matter change with temperature. Pressure of a gas. Electrical Resistance. Q11 The molecules of the alcohol in the thermometer will either gain energy or lose energy. If they have more energy, they expand. If they have less energy, they contract. Ways To Measure Temperature Temperature is given the symbol (T), and can be communicated using one of the three different temperature scales. Daniel Gabriel Fahrenheit - Fahrenheit Scale ( F) Temperature Scale in 1724 32 = Freezing point of water and 212 = Boiling point of water Divided this interval 180 parts. Anders Celsius- Celsius Scale ( C) Developed the Celsius scale in 1742 for meteorological observations. 0 = Boiling point of water and100 = Freezing point of water Reversed after his death in 1744. Lord William Kelvin- Kelvin Scale (K) Calculated that molecular motion stops at -273 C, which he called absolute zero. (1847) Uses same divisions as the Celsius scale. Q12 Convert It! All three scales are used, and therefore it is important to be able to convert between them. Fahrenheit to Celsius: T( C) = (T( F) - 32) The average temperature at Earth s surface is F, what is the temperature in Fahrenheit? T( C) = ( F - 32) Celsius to Kelvin: Celsius to Fahrenheit: T( F) = T( C) + 32 T(K) = T( C) + 273 T( C) = ( F - 32) Q13 T( C) = 1 C T(K) = 288 K Communicating Temperature Temperature The actual temperature at a given point and time. Mean Temperature Average Temperature Add all the readings and then divide by the number of readings. Temperature Range Difference between the highest and lowest temperature. Subtract the lowest temperature from the highest. Example: Find the mean temperature and the temperature range for 0 C, 22 C and 42 C. Mean = 38 C Range = 28 C Q14
Q1 Back to Our Budget A budget compares your income with your spending. What would happen to the temperature of the Earth if Insolation = Outgoing Radiation Insolation > Outgoing Radiation Insolation < Outgoing Radiation Based on our budget, if there was no atmosphere, the Earth would be -18 C. Remain the Same Increase Decrease Keeping Things Comfortable! The surface of the Earth is an average temperature of 1 C. Warmer than expected because of the greenhouse effect. Gases in our atmosphere act as a blanket of just the right thickness to keep things comfortable. Main Greenhouse Gases: Water Vapor Carbon dioxide Methane Nitrous oxide Q16 Let s See How It Works! Q17 Let s See How It Works! The Earth radiates energy as long-wave radiation. Greenhouse gases absorb some of this energy. Reradiate it back toward the Earth, causing it to heat up. Q17 The sun s short-wave radiation enters the atmosphere. Some is reflected back into space, and some is absorbed by the Earth s surface. The Earth becomes warmer!
Goldilocks Planet Venus global temperature is 462 C. Atmosphere consists of large amounts of carbon dioxide and water vapor. Mars global temperature is -60 C. Atmosphere consists of mainly of carbon dioxide but it is very thin. On A Local Level Throughout the country, there are certain temperature characteristics based on location. Mountains are colder. Cities are warmer. Maine is colder than Texas. Q18 What factors about a location might influence temperature? Elevation/Altitude Latitude We will investigate these factors using data! Proximity to water Color