Temperature and the Atmosphere

1. Temperature and the Atmosphere

2. Without heat there is no weather. • The most influential factor effecting weather in the atmosphere is heat.

3. Solar Heating • Most of heat found in our atmosphere comes from the Sun. • The Sun produces a massive amount of energy, every moment of every day. • Most of the energy is radiated outward into the furthest reaches of the Solar System.

4. Electromagnetic Spectrum • The heat produced by the Sun travels from the Sun to the Earth via waves known as electromagnetic waves. • All these waves together are known as the electromagnetic spectrum. • Broken into three separate categories • Ultra violet waves - the shortest • Visible light - the medium sized waves • Infrared - the longest waves • Microwaves and radio waves

5. Ultraviolet Waves • Waves measuring under 0.4 micrometers • These short waves are extremely dangerous to living organisms. • Long term exposure to ultraviolet radiation would seriously hurt and even kill most life forms on Earth, including humans. • Most of these waves never reach the surface of the Earth. • They are either absorbed, or reflected and bounced away by molecules in the upper atmosphere.

6. Visible Light Waves • Waves with a length of between 0.4 and 0.7 micrometers • Can be detected by the human eye. • Shorter visible light wavelengths, are bluer in color, while longer visible light wavelengths are redder in color. • The wavelengths detectible by the human eye represent only about 3% of the total electromagnetic spectrum.

7. Infrared Waves • Infrared waves are commonly referred to has heat rays. • Heat is in infrared radiation.

8. Transferring Heat • There are three natural processes that can be used to transfer heat. • Radiation • conduction • Convection

9. Radiation • All objects radiate energy and heat. • Radiation leaves an object in the form of waves. • The hotter an object, the shorter the wavelength of this radiation. • The infrared waves, or heat rays leave the hot fire, and radiate out towards your hands.

10. Conduction • As one molecule is heated it begins to move and shake rapidly. • As it does so, it passes some of its heat energy to other molecules around it. • All the molecules of an object pass heat from one to another, until they are all hot. • As the hotdog cooks, the fire heats the end of the hanger. • Eventually the end we are holding will become too hot for us to handle. • Heat was transferred from the flames to the metal, and than from molecule to molecule in the hanger via conduction until it reached your sensitive fingers

11. Convection • Convection takes place when heated molecules move from one place to another, taking the heat with them. • Common in both the atmosphere, as well as in the oceans. • Heated air in our atmosphere expands, becoming less dense and rises upward. Cooler air rushes in to replace the air that lifted up. • As warm air rises, and cool are falls, a giant circular pattern is created. • Eventually the warmer air cools, and begins to fall again.

12. Objects React To Heat • What happens to that heat once it arrives at a destination depends on a number of factors. • Size of object • Current temperature of object • Material object made of • As heat reaches its destination it will either be absorbed, reflected, scattered, or transmitted

13. Heat Absorption • Heat enters an object, warming it. • The longer the object is exposed to the heat source, the more heat that it absorbs. • Different objects absorb heat at different rates. Some objects are excellent absorbers, while others are very poor absorbers. • Dark colored objects absorb well • Absorb more light • Light colors do not absorb heat well

14. Heat Reflection • The opposite of absorption • Heat energy is bounced, or reflected off in the opposite direction. • Objects which are good at absorption are as a result poor reflectors, and vice versa.

15. Scattering • The waves of light, heat, and ultraviolet radiation interact with the particulates found in the atmosphere and water • Dust, gases, water and pollution • Electromagnetic waves hit these particulates they are bounced off in random directions. • Direction depends on size and shape of particles. • Smaller wavelengths, such as blue light tend to scatter more than longer wavelengths. • This is why the sky looks blue

16. Heat Transmission • Occurs when electromagnetic energy is allowed to pass completely through an object • glass window, or through water in a lake or stream.

17. Adiabatic Temperature Changes • Heated air expands becoming less dense and lighter • Rises upwards and continues to expand because of decreasing air pressure • Spreading out of molecules requires energy and air lose energy and temperature drops • Cooler air begins to fall and becomes compressed causing it to heat up and temperature rises

18. Latent Heat • Water allows the atmosphere to store heat • Stored heat is latent heat • Water evaporates off Earth’s surface and rises into air carrying heat into the atmosphere • Water condenses and falls to ground as precipitation and heat returns to ground

19. The Heat Budget • Heat coming into the atmosphere is generally balanced with the heat leaving the atmosphere • This keeps the planet’s temperature stable • It may vary from day to day and place to place but overall it relatively stable

20. Heat And Weather • Unequal heating of the surface of the Earth is the principal cause of weather • As the gases in Earth’s atmosphere heat up, they begin to expand, or spread out. Air begins to rush outward towards places where there is less pressure. • This rushing air is what causes wind.

21. Latitude Affects Temperature • Latitude – the distance from the Earth’s equator contributes to unequal heating of the Earth’s surface. • The farther from the equator a location is the less sunlight it receives and thus less heat.

22. Day Length Affects Temperature • The longer that a day lasts, the more time that there is for Earth to absorb energy from the Sun. • Longer days result in warmer days • Shorter days result in cooler days. • On the equator the length of days changes very little throughout the year. • Day is almost exactly 12 hours and night is 12 hours. • The further away that one travels from the equator the more variation in length of day that will be observed.

23. Atmospheric Obstructions Affect Temperature • Clouds can block light and heat from reaching from reaching the surface • Causes a drop in temperature

24. Land And Water Affect Temperature • The atmosphere of the Earth is primarily heated by radiation coming off of the Earth. • 50% of the Sun’s energy is absorbed by the Earth, and than released back into the atmosphere. • The temperature of the air in a location can be effected by the materials found on the surface. • Forest (absorb) vs. Desert (reflect) • Water absorbs heat slowly and releases heat slowly

25. Our Atmosphere Transfers Heat • Earth is constantly trying to balance temperature differences. • Cooler areas attract warm air • Warmer areas push air outward in an attempt to cool itself down • Locally air rushes from one place to another, as it attempts to balance temperature and pressure

26. Homework • Chapter 3 Section 2 Assessment Questions • Winds Worksheet • Weather Worksheet