Atmosphere

1. Atmosphere Water and Air… the two essential elements on which life depends have become global garbage cans

2. Essential Standards EEn.2.5 Understand the structure of and processes within our atmosphere. • EEn.2.5.1 Summarize the structure and composition of our atmosphere. • EEn.2.5.2 Explain the formation of typical air masses and the weather systems that result from air mass interactions. • EEn.2.5.3 Explain how cyclonic storms form based on the interaction of air masses. • EEn.2.5.4 Predict the weather using available weather maps and data (including surface, upper atmospheric winds, and satellite • imagery). • EEn.2.5.5 Explain how human activities affect air quality. EEn.2.6 Analyze patterns of global climate change over time. • EEn.2.6.1 Differentiate between weather and climate. • EEn.2.6.2 Explain changes in global climate due to natural processes. • EEn.2.6.3 Analyze the impacts that human activities have on global climate change (such as burning hydrocarbons, greenhouse effect, • and deforestation). • EEn.2.6.4 Attribute changes to Earth’s systems to global climate change (temperature change, changes in pH of ocean, sea level • changes, etc.).

3. Atmospheric composition Structure and processes

4. Assignment! • Create a chart for the next 2 weeks (Dec 20th will be the last day) • Each day we will observe the cloud types during your class • We will record the cloud types along with the weather each day • If the weather changes during the day – it is your responsibility to change / add to the weather for that day • You will write a brief conclusion at the end stating if you see a difference in the weather depending on the cloud type

5. Brief Review • What was the composition of the original atmosphere like? • What evolved on Earth that drastically changed the composition? • How did these organisms change the composition of Earth’s atmosphere? Mostly methane, carbon dioxide, and ammonia. Deadly to living organisms today Plants Drastically increased the oxygen content

6. What is the structure of the atmosphere? • 4 layers from bottom to top • last layer sometimes divided in half to make 5 • Troposphere – lowest layer, weather happens here • Stratosphere – next layer up, jets fly here, ozone found here • Mesosphere – meteors burn up here • Thermosphere – hottest layer, space stations here • Ionosphere – where auroras take place • Exosphere – outer layer, space stations

7. How are layers divided? • According to temperature trends • Each layer is separated by a pause • Tropopause between troposphere and stratosphere etc • What happens to the temperature in each layer of the atmosphere? • Troposphere – temp decreases • Stratosphere – temp increases • Mesosphere – temp decreases • Thermosphere – temp increases

8. What is the atmosphere made of? • Mostly nitrogen (N) – about 78% • Oxygen (O) – about 21% • Carbon Dioxide (CO2) – about .03%

9. Remember radiant energy? • Comes from the sun • In many forms • Represented by the electromagnetic spectrum! • When it comes in contact with the ionosphere it can often create light shows called _________________. auroras

11. Assignment! • Draw the atmosphere on your own! • You will need: • Large paper • Colored pencils • To label each layer • Draw an arrow at the bottom pointing to the right and label it temperature • Draw an arrow to the left side pointing up and label it altitude • Add ground • Label each layer of the atmosphere (place the ozone layer where it goes in green) • Draw a continuous line up your paper through each layer to indicate how the temperature changes with elevation • Add in a picture in each layer to indicate what is special about it • Turn in

12. Assignment! • Layers of the atmosphere worksheet • Turn in when finished

13. How does air move? • In large pockets called air masses • Air masses move based on pressure • High pressure systems move toward low pressure systems (high  low)

14. How do air masses affect weather? • They pick up the characteristics of the area in which they form • They are very large (up to 1600km) making weather fairly consistent • They carry temperature and moisture over the area where they are moving

15. How are air masses classified? • Overall temperature • Where they formed • 4 major types • Polar –cold temps • Tropical –warm temps • Continental –dry air • Maritime – wet air (high water vapor content) • Arctic – very cold and dry • Type of air mass will consist of 2 words

16. What kind of air masses influence North American weather? • Mostly influenced by maritime tropical (mT) and continental polar (cP) air masses

17. What are continental polar air masses like? • Cold dry winters • Cool dry summers • Not associated with precipitation • Subject to the “lake effect” when crossing the Great Lakes • Pick up moisture from the Great Lakes and may bring some precipitation

18. What are maritime tropical air masses like? • Warm and loaded with moisture • Usually unstable • Source of most precipitation in the Eastern US

19. What are maritime polar air masses like? • Come from the North Pacific • Cold and dry turns into mild and humid • Unstable • Accompanied by low clouds and showers – snow in mountains

20. What are continental tropical air masses like? • Least influence in North America • Hot and dry • Only occasionally affect weather outside their source region

21. How do air masses move again? • Air pressure • Exerted in all directions • Object pushes back on the air with exactly the same force • Measured using a barometer • Typical air pressure: • 1 atmosphere (ATM) • 760 mm Hg (mercury) • 980 millibars weather and air pressure

22. How does pressure affect air masses? low high • Air masses move from ____________  ____________ pressure • Causes wind • Unequal heating of Earth creates pressure differentials • How does land heat up compared to water? • Solar radiation is the ultimate source of wind • 3 factors • Pressure • Coriolis effect • friction

23. Assignment! • Build a barometer • You will need • A beaker • A balloon • A rubber band • A sheet of notebook paper • A pencil • We’ll check your barometer daily and compare it to actual barometric pressure

24. Fronts Come back to back

25. How can we tell where air masses are going? • Look for pressure • Red H is high pressure • Blue L is low pressure • Sometimes pressure is shown on maps in isobars, similar to isotherms • Iso means equal • Isobars are lines showing equal pressure

27. What is weather like in a high pressure system? • Sunny • Clear • Dry • High day and low night temperatures • Calm • Dew and frost • Fog and mist • Stable sinking air

28. What is weather like in a low pressure system? • Cloudy • Little sun • Wet • Mild temperatures for the time of year • Windy • Changeable weather • Unstable rising air

29. What is the difference in a cyclone and an anticyclone? Anticyclones Cyclones Low pressure Air rises and separates Spin Counterclockwise in northern Clockwise in southern • High pressure • Air pushes together and sinks • Spin • Clockwise in northern hemisphere • Counterclockwise in southern

30. A C D B D

31. What is a front? • The area where 2 air masses meet • 4 kinds of fronts • Warm front • Cold front • Stationary front • Occluded front • Each front has a symbol • Side of the line the symbols are on indicate direction of movement

33. What does each front mean? • Warm front – warm air is replacing cold air • Cold front – cold air is replacing warm air • Stationary front – air masses are not moving due to similar pressures • Occluded front – warm air is pushed up due to cold air moving in from both directions front animation

34. What happens when cold and warm air meet? • Cold air sinks and warm air rises • Warm air carries moisture • Moisture condenses • Clouds form • Once air is saturated with moisture, precipitation in some form occurs

35. What happens before and after a warm front? Before After Warm and more humid Clearing clouds Rising barometer Temp and dew point are close • Cool or cold temps • Falling barometer • Increasing, thickening clouds • Light to moderate precipitation • Temp and dew point get closer together

38. What is dewpoint? • The temperature at which air is saturated enough for water to condense • High dewpoint – temperature and dewpoint are close together • Low dewpoint – temperature and dewpoint are far apart • ALWAYS a dewpoint

39. What happens before and after cold fronts? Before After Lower temps Rising pressure Showers then clearing skies Temp and dewpoint get further apart • Warm • Falling barometer • Increasing clouds • Short period of precipitation • Temp and dew point close together

42. What to expect from a stationary front? • Changing winds and temperatures when crossing from one side of the front to the other • Similar pressure in air masses keeps them from moving

43. What can you expect from an occluded front? • Developing cyclones usually have a warm front and a faster moving cold front to wrap around them • Occluded fronts form when cold air catches up to a warm front that is trapped behind a cold front already in place • Change in temp, dewpoint, or wind possible jet stream

44. Assignment! • Predicting weather • Edheads weather prediction • We’ll do this as a group

45. Assignment! • Complete the forecasting weather map worksheet • Put in the box when you are finished

46. Clouds How they form and what they mean

47. What happens as water evaporates? • Humidity – the amount of water in the air • Amount of water vapor increases = higher humidity • Air pressure increases as amount of water vapor increases • Air is saturated when water entering air = water returning to surface • Warm air contains more vapor than cold air

48. How is humidity measured? • Using a hygrometer • Relative humidity – ratio of actual amount of water in the air compared to the amount of water air can hold at that temperature and pressure • If amount of water vapor is constant, what will happen to the humidity if you raise the temperature? Lower it?

50. So how do clouds form? • Temperature can change without heat input or loss • These changes are called adiabatic temperature changes • Happens when air is compressed or expanded • Expansion cools • Compression warms