Understanding Weather and Climate: Water Phase Transitions and Cloud Formation

1. Notes Points Name _____________________________________ Period ________

2. Chapter 24 Standards 6a. Students know weather (in the short run) and climate (in the long run) involve the transfer of energy into and out of the atmosphere. 6b. Students know the effects on climate of latitude, elevation, topography, and proximity to large bodies of water and cold or warm ocean currents.

3. CHAPTER 24 – WEATHER

4. I. 23.1 – Atmospheric Moisture

5. There are three different states/phases of water. Solid Known as ice Water molecules are held in one place and are most packed together. Liquid Known as water Water molecules are moving around and are moderately packed together. Gas Known as water vapor Water molecules are moving around and are most spread out. (Color the picture.)

6. Changing Forms of Water Water changes from one phase to another because of latent heat. Latent heat is the heat energy that a substance absorbs from its surroundings or releases into its surroundings.

7. There are processes that change the state of water. Condensation Process of water vapor (gas) changing into water (liquid). Energy is released into the surrounding air. Clouds form because of this process.

8. Evaporation Process of water (liquid) changing into water vapor (gas). Energy is absorbed from the surrounding air while water vapors are released into the surrounding air. Most evaporation takes place at the equator where there is the largest amount of solar energy . Water evaporates from lakes, ponds, streams, and soil. Plants release water into the environment through process of transpiration.

9. Sublimation Process of a solid changing directly into a gas. When air is dry and temperature is below freezing, ice and snow sublimate into water vapor. Water vapor can also turn directly into ice under the right conditions.

10. The Water Cycle Earth’s water cycles over and over again in what is called the water cycle. The water cycle is the movement of water among the atmosphere, the land, and the oceans through different processes such as evaporation and condensation. Latent heat affects the amount of water vapor and temperature of the atmosphere which affects precipitation and climate. (Color and label the picture.)

11. Clouds A cloud is a collection of millions of tiny water droplets or ice crystals that fall slowly through the air. Clouds form as water vapor rises, cools, and condenses. Clouds are classified by their shape (form) and their altitude (height above the earth’s surface).

12. Clouds Categorized by Forms There are three cloud forms: stratus clouds look like flat layered sheets cumulus clouds look puffy cirrus clouds look like strands of curly hair Adding the word “nimbus” or “nimbo” to any of the above means that precipitation is falling from the cloud.

13. Types of Cloud Forms CUMULUS STRATUS CIRRUS

14. Clouds Categorized by Altitude There are 3 altitude groups: low clouds 0m – 2,000m middle clouds 2,000m – 6,000m add the prefix alto- high clouds above 6,000m add the prefix cirro-

15. Cloud Formation Small particles and water molecules are suspended in the air. The water molecules collect together and form larger water droplets. This is condensation. When the rate of condensation is greater than the rate of evaporation, clouds form. The rate of evaporation decreases as temperature decreases (higher in altitude) so cooling of air may lead to a greater condensation rate. There are four processes that cause the cooling of air for cloud formation. Adiabatic Cooling Mixing Lifting Advective Cooling

16. Adiabatic Cooling and Cloud Formation Adiabatic cooling is the process by which the temperature of an air mass decreases as the air mass rises and expands. As air mass rises, surrounding atmospheric pressure decreases. The lower pressure causes the molecules in the rising air mass to spread out. Since the molecules are spread out, less energy is transferred and this decreases the temperature. Adiabatic lapse rate is the rate at which the temperature of a parcel of air changes as the air rises or sinks. The slower the rate of cooling of moist air results from the release of latent heat as the water condenses.

17. Mixing and Cloud Formation • Some clouds form when there is a “mixing” of two bodies of moist air of different temperatures. • This temperature change can cool the combined air to below its dew point and results in cloud formation.

18. Lifting and Cloud Formation • Air can be forced upward or lifted in a couple of ways. • When an air mass meets and goes up a side of a mountain or when the air mass is cold. • When an air mass pushes a less dense mass of warmer air upward. • As air rises, it expands and cools. As a result, clouds form.

19. Advective Cooling and Cloud Formation • Advective cooling is the process by which the temperature of an air mass decreases as the air mass moves over a cold surface. • If the surface is colder than the air, it will take the heat/energy from the air. • The temperature of the air will cool. • If the air cools below its dew point, clouds will form.

20. Write 10 questions for this section. Highlight key words and phrases. Draw a picture.

21. Summary (one paragraph) – Page 3 The three stages/forms of water are _____________, _____________, and ____________. Latent heat is ________________________________. The water cycle is _________________________________. A cloud is ___________________________. The three main cloud forms are __________, __________, and __________. The four processes that cool air for cloud formation are __________, __________, __________, and __________.

22. II. 24.1 – Air Masses

23. Air Moves Unequal heating of Earth’s surface results in differences in air pressure. Equatorial region receives more solar energy which results in warm air. Polar regions receive less solar energy which results in cold air. Differences in air pressure result in movement of air (high pressure to low pressure) and this creates wind patterns. Warm air has less (low) pressure and rises. Cold air has more (high) pressure and sinks. General worldwide movement of surface air is from the poles towards the equator.

24. Air Masses Air masses are large bodies of air which have similar temperature and amounts of moisture. Air masses that form over polar regions are cold and dry. Air masses that form over tropical regions are warm and moist. (Color the picture.) Air Masses

25. Types of Air Masses Continental Air Masses – air masses formed over land (dry) continental polar (cp) – air mass formed over land in the polar region dry and cold continental tropical (ct) – air mass formed over land in tropical region dry and warm Maritime Air Masses – air masses formed over ocean (moist) maritime polar (mp) – air mass formed over ocean in polar region moist and cold maritime tropical (mt) – air mass formed over ocean in tropical region moist and warm

26. (Color the picture.) Types of Air Masses

27. Write 5 questions for this section. You should have a total of 15 questions. Highlight key words and phrases. Draw a picture.

28. Summary (one paragraph) – Page 4 Unequal heating of Earth’s surface results in _______ ____________________. Warm air has __________ pressure and __________. Cool air has __________ pressure and __________. Air masses are _______________________________. The two main types of air masses are _____________ air masses and _____________ air masses.

29. Notes Points Name _____________________________________ Period ________