National Weather Service Shreveport www.srh.noaa.gov/shv The Atmosphere
The Atmosphere • Layers of the Atmosphere • Air Pressure • Transfer of Heat Energy • Earth-Atmosphere Energy Balance • Hydrologic Cycle
Layers of the Atmosphere • Troposphere • Lowest Layer • This is where we live • 8 to 12 miles in height • Weather occurs • Temp decreases with height • Stratosphere - Second lowest layer - Temp increases with height - Ozone (03) layer - Absorbs most of the damaging ultraviolet sunlight (UV-B) • Mesosphere - From ~30 to 53 miles up • - Temp decreases - Majority of meteors burn up • Thermosphere - Upper atmosphere 53 to ~430 miles up • - Very few molecules Still would feel cold Ozone Layer
Upper Air - Radiosondes Radiosondes are released from the inflation building and move up through the atmosphere (20 miles) sending back weather information along the way.
Launch of a Weather Balloon The balloon with the radiosonde is launched twice daily...at 11z and 23z (GMT)...unless otherwise necessary.
Air Pressure • Density of Molecules decreases with height. • Although the atmosphere goes up to 184 miles, half of the atmosphere is in the first 18,000 feet or 3.4 miles. • Less molecules (same composition) higher up makes it is harder to breath than at sea level. • Air Pressure is converted to Sea Level Pressure to observe surface low and high pressures. (otherwise the Rocky Mts. would be always be low pressure and the oceans would be areas of high pressure). • Pressure also dependent upon Temperature (We will perform an experiment on this)
Draw Isotherms. 26.64 -- 902 Hurricane Katrina (2005)
2 Experiments • Crunch Time (5-10 min) • Effect of Heat on Pressure • Items used: • 2 empty 2-liter bottles • hot tap water • Go with the Flow (3-5 min) • Creating Low Pressure • Bernoulli’s Principle • Items used: • 2 empty soda cans • level surface
Crunch Time Experiment Capped Bottle eventually collapsed. WHY????? - Air inside that bottle cooled off - Cooling takes place because the atoms inside the bottle loose energy as they collide with the bottle side that is exposed to the cooler surrounding air. But why did it collapse… - As atoms loose energy…their velocity decreases resulting in a decrease of pressure in the bottle. - Since the pressure inside the bottle is less than outside…the bottle is crushed. The uncapped bottle remains unchanged. WHY?? As air cools inside the bottle, outside air moves into the bottle to equalize the pressure on both sides.
Go with the Flow • Air flows from high to low pressure. • The air blown between the cans created an area of low pressure between the cans and induced high pressure surrounding the cans. This caused the cans to move from high to low pressure. This is known as Bernoulli’s Principle.
Transfer of Heat Energy • Radiation • Conduction • Convection
Radiation • The transfer of heat energy by electromagnetic radiation. • Earth is heated by this process. - various substances on earth (dirt, rocks, water, concrete, sand, etc.) absorb this energy and their heat level is raised. They transmit that heat through mainly convective heat transfer to the surrounding atmosphere, and eventually to us.
Conduction • The transfer of heat energy from one substance to another or within a substance. • Very effective in heating metals • Air is a poor conductor.
Convection • The transfer of heat energy in a fluid. • Commonly seen in the kitchen when you see boiling water • Air in the atmosphere acts a fluid
Transfer of Heat EnergySummary • Radiation • Conduction • Convection
Thermometers • Max Min Temperature System (MMTS) • Thermistor • Cotton Region Shelter • Max and Min Thermometers • Alcohol (min) • Mercury (max)
The Effects of Clouds • Nighttime: clouds keep the earth warmer • Daytime: clouds keep the earth cooler
Greenhouse Effect The greenhouse effect is the rise in temperature that the Earth experiences because certain gases in the atmosphere (water vapor, carbon dioxide, nitrous oxide, and methane, for example) trap energy from the sun. Without these gases, heat would escape back into space and Earth’s average temperature would be about 60ºF colder. Because of how they warm our world, these gases are referred to as greenhouse gases. Prevents heat loss mainly from convection (air movement carrying away the heat)
Hydrologic Cycle • Evaporation • change of water from a liquid to a gas. • Stepping out of a shower or swimming pool • Transpiration • evaporation of water from plants • Condensation • water vapor returns to a liquid (i.e., clouds, fog, mist, dew or frost) • Precipitation • Runoff • Excessive precipitation that cannot be absorbed by the ground.
Experiment • Water Everywhere (10 min) • See Hydrologic Cycle in action • Items used: • sandwich bag • glass jar • hot tap water • ice cubes
Questions A sunburn is caused by which method of heat transfer: A.) Radiation B.) Convection C.) Conduction D.) Visible Light Answer: Radiation
Questions The layer of the atmosphere where most of the world’s weather occurs is: A.) Thermosphere B.) Stratosphere C.) Troposphere D.) Hemisphere E.) Mesosphere Answer: Troposphere
Questions At night, temperatures will normally be cooler under cloudy skies than under clear skies. A.) True B.) False Answer: False
Questions The brief cloud that forms when you exhale on a cold winter day was formed because of: A.) Precipitation B.) Convection C.) Evaporation D.) Condensation E.) Runoff Answer: Condensation
Questions The hydrologic cycle is: A.) Convection, conduction, condensation, Radiation B.) Rain, Sunshine, Condensation, Flood C.) Evaporation, Transpiration, Condensation, Precipitation, Runoff Answer: C
Questions If you feel the heat in the handle of a cooking pot, that heat was transferred to the handle by: A.) Convection B.) Conduction C.) Radiation Answer: Conduction
Questions It is _____ to breath on top of a mountain than at sea level because there are ______ oxygen molecules at the summit. A.) easier / more B.) harder / more C.) easier / less D.) harder / less Answer: harder / less
Acknowledgments • Jetstream website – Southern Region Headquarters , National Weather Service • www.srh.noaa.gov/srh/jetstream