Warmup

1. Warmup • Compare and contrast Tornado Watches with Tornado Warnings. • Compare the wind speed of an F5 tornado and a Category 5 Hurricane. • Why are hurricanes considered the most powerful storms on Earth?

2. 2.5.4c Moisture, Precipitation, and Clouds

3. Objectives • Today I will be able to: • Evaluate the most important gas in the atmosphere. • Compare and contrast saturation and relative humidity.

4. Key Points - Moisture • Water vapor is the most important gas for understanding atmospheric processes. • Water vapor makes up 0-4 % of atmospheric gases. • Air that has reached its water vapor capacity is said to be saturated. • Warm, saturated air contains more water vapor than cold air. • Relative humidity is the ratio of air’s water-vapor content to its capacity to hold water vapor at that same temperature.

5. Water in the Atmosphere • Water exists in three different forms. • What are they? • SOLID Examples: Snow, ice • LIQUID Examples: Rain, water • GAS Examples: Clouds, water vapor • How do each of these forms of water influence weather?

6. Water in the Atmosphere • When it comes to understanding atmospheric processes, water vaporis the most important gas in the atmosphere. • Why do you think water vapor is so important?

7. Water in the Atmosphere • Even though water vapor is important, it only makes up from 0 – 4% of the atmospheric gases. • When have you felt water vapor at close to 4%? • What about 0%? • How do you know? • Water vapor is the HUMIDITY that you feel in the air!

8. Water in the Atmosphere • What do you think the word “SATURATED” means? • What do you think it would mean if air is Saturated? • Air that has reached its water vapor capacity is said to be saturated.

9. Water in the Atmosphere • Warm, saturated air contains more water vapor than cold air • Dew point is the temperature to which air is cooled to reach saturation. • The point at which condensation can occur • When have you noticed the humidity more, in the summer or in the winter? • That’s because warm air can hold more water vapor!

10. Water in the Atmosphere • Relative humidity is the ratio of air’s water-vapor content to its capacity to hold water vapor at that same temperature. • Relative humidity indicates how near the air is to saturation, not the actual quantity of water vapor in the air. • Relative Humidity varies with temperature. • Cooling air increases its relative humidity. • Warming air decreases its relative humidity.

11. 1% :2% • 1%:4%

12. 2%: 3% (cooler) 2/3 • 2%: 4% (warm) 2/4

13. Water in the Atmosphere • Relative Humidity – • Why does lowering the air temperature cause Relative humidity to increase? • Because colder air cannot hold as much water vapor! • Why does increasing air temperature cause relative humidity to decrease? • Because warm air can hold more water vapor and it will take more water vapor for it to become saturated.

14. Check In Questions Answer the following questions: • What gas is most important for understanding atmospheric processes? • Water vapor makes up what fraction of atmospheric gases? • Which holds more water vapor: warm air or cool air? • Henderson has a humid climate. What are evidences of humidity that you have seen? • How is the humidity different from the summertime to the wintertime? • Why is the air in buildings so dry in the winter?

15. Matching- answer A, B or C for each of the situations. Situation • Water vapor is added • Air temperature decreases • Water vapor is removed • Air temperature increases Change in Relative Humidity: • Increases • No change • Decreases

16. Measuring Moisture • Invent a machine that measures Relative Humidity and Water Saturation in the air. • Draw a picture of the machine • Write a detailed description of how the machine works. • Create instructions for how to use the machine. • You will be judged based on creativity and neatness. Be specific about how it works!

17. Warmup • Air that has reached its water-vapor capacity is said to be: a. Dry b. unstable c. stable d. saturated • The ratio of air’s water content to its capacity to hold water at the same temperature is: a. Vapor pressure b. relative humidity c. specific humidity d. wet adiabatic rate • Water vapor makes up what fraction (%) of atmospheric gases?

18. Warm up 12/2 • Water vapor makes up what percentage of atmospheric gases? • What is the most important gas for understanding atmospheric processes? • What is air called that has reached its water-vapor capacity? • Which type of air can hold the most water-vapor? Cold or warm? • Explain relative humidity.

19. Lifting Air - Objectives • Today, I will be able to: • Describe how air is lifted to form clouds. • Differentiate between the types of clouds by making a poster (if you finish all your work) • Describe the weather associated with the different types of clouds.

20. Key Points - Clouds • When air is compressed the air temperature rises and the air molecules move faster. • Processes that lift air include orographic lifting, frontal wedging and convergence. • Examples of condensation nuclei include dust, smoke and salt particles.

21. Lifting Air • When air is compressed the air molecules move faster and the temperature rises. • Air compression causes changes in temperature even though heat isn’t added or subtracted. • When air is allowed to expand, it cools. • When air is compressed, it heats up.

22. Lifting Air • Four mechanisms that cause air to rise are: • Orographic Lifting • Frontal Wedging • Convergence • Localized Convective Lifting

23. Lifting Air • Orographic Lifting • Orographic lifting occurs when mountains act as barriers to the flow of air, forcing the air to ascend.

24. Lifting Air How does the relatively flat areas form clouds? • Frontal Wedging • A front is the boundary between two adjoining air masses having contrasting characteristics.

25. Lifting Air • Convergence • Convergence occurs when two air masses converge. The air flows together and rises.

26. Lifting Air • Localized Convective Lifting • Localized convective lifting occurs where unequal heating on earth’s surface causes pockets of air to rise.

27. Lifting Air Clouds form because as you go up in elevation, it gets colder. Cold air cannot hold as much water vapor so it transforms into clouds. Cool, expanded air Warm, compressed air

28. Lifting Air – Creating Clouds • When air expands to form clouds, the water vapor is transformed to clouds by condensation. • Generally, there must be a surface for water vapor to condense on. • Condensation nuclei are tiny bits of matter that serve as surfaces on which water vapor condenses when condensation occurs in the air. • Examples of condensation nuclei include dust, smoke and salt particles.

29. Check In Questions • What happens when air is compressed? • Name the 4 processes that lift air. • Why are condensation nuclei important? • Name 3 examples of condensation nuclei.

30. Brochure • Create a handout that shows the different ways air is lifted to form clouds. • Front flap: • Name of the handout • Your name and class period • Inside flaps/back flap: • Title each flap with the four ways air is lifted • Draw a picture under the title on each flap • Explain how air is lifted in your own words for each of the flaps.

31. Brownie Ticket • Which of the following occurs when air is compressed? • Air temperature rises • Air temperature cools • Air molecules move faster • Both a and c • Name 2 examples of condensation nuclei. • Which of the following is NOT a process that lifts air? • Convergence • Orographic lifting • Divergence • Frontal wedging

32. Warm up – 12/3 • What happens to air when it is compressed? (2 things) • Name 3 examples of condensation nuclei • Explain orographic lifting. • Explain frontal wedging • When are days and nights equal in length – during a solstice or an equinox? • The heating of the lower layer of the atmosphere from radiation absorbed by gases is called: ______________.

33. Clouds Objectives • Today I will be able to: • Classify clouds based on shape and height.

34. Clouds • Now we are going to learn about the different types of clouds and how they are classified. • Clouds are classified based on their form (shape) and height.

35. Clouds • Cloud types by FORM • There are three basic forms of clouds. All other clouds one of these three or are combinations or modifications of them: • Cirrus • Cumulous • Stratus

36. Clouds by Form • Cirrus (cirrus = “curl of hair”) are clouds that are high, white, and thin.

37. Cumulus

38. Stratus

39. Highest Clouds • Cirrus • Cirrostratus • Cirrocumulus

40. Mid altitude clouds • Altostratus • Altocumulus • Nimbostratus

41. Low Clouds • Cumulus • Stratus • Cumulonimbus (thunderstorms, hail, tornados) • Stratocumulus