18.1 Engage: What Causes Condensation?

18.1 Engage: What causes condensation?

1. Watch the time lapse video of a glass of water with ice in it.
2. At what time did water first appear on the outside of the glass in the video?

1. Where did the water that formed on the beaker’s outer surface come from?

1. Describe a process in nature that results from condensation with a change in temperature?

18.1 Learning Goals

1. Identify the gas that is the most important for understanding atmospheric processes.
2. Describe what happens during a change of state.
3. Compare and contrast the abilities of cold air and warm air to hold water vapor.
4. Define relative humidity.
5. Describe the factors that affect the relative humidity of air.

18.1 Notes - Water in the Atmosphere

Water’s Changes of State

- ______is any form of water that falls from a cloud.

- When it comes to understanding atmospheric processes, water vapor is the most important ______in the atmosphere.

Water’s Changes of State

- Solid to Liquid

- The process of changing state, such as ______ice, requires that ______be transferred in the form of heat.

- ______is the energy absorbed or released during a change in state.

- Liquid to Gas

- ______is the process of changing a liquid to a gas.

- ______is the process where a gas, like water vapor, changes to a liquid

Water’s Changes of State

- Solid to Gas

- ______is the conversion of a solid directly to a gas without passing through the liquid state.

- ______is the conversion of a vapor directly to a solid.

Humidity

- ______is a general term for the amount of water vapor in air.

- ______

- Air is ______when it contains the maximum quantity of water vapor that it can hold at any given ______and ______.

- When saturated, ______air contains ______water vapor than cold saturated air.

Humidity

- Relative Humidity

- ______is a ratio of the air’s actual water-vapor content compared with the amount of ______air can hold at that temperature and pressure.

- To summarize, when the water-vapor content of air remains constant, ______air temperature causes an increase in relative humidity and raising air temperature causes a decrease in relative ______.

Humidity

- ______

- Dew point is the temperature to which a parcel of air would need to be cooled to reach saturation.

- Measuring Humidity

- A ______is an instrument to measure relative humidity.

- A ______is a hygrometer with _____- and ______-bulb thermometers.

- Evaporation of water from the wet bulb makes air temperature appear lower than the dry bulb’s measurement.

- The two temperatures are compared to determine the relative humidity.

Copy Figure 2 on pg. 505 in the space below

Dew Point Practice

18.1 Review and Reinforcement

1. What is the most important gas for understanding atmospheric processes?

1. What happens to heat during a change of state?

1. How does the temperature of air influence its ability to hold water?

1. What does relative humidity describe about air?

1. List two ways that relative humidity can be changed?

1. What does a low dew point indicate about the moisture content of air?

18.2 Engage: Clouds on Mountains

1. Watch the video: The Process of Adiabatic Cooling and Heating.
2. Why do clouds form at the top of mountains?

18.2 Learning Goals

1. Describe what happens to air when it is compressed or allowed to expand.
2. List the four mechanisms that cause air to rise.
3. Compare and contrast movements of stable and unstable air.
4. Describe the conditions in air that favor condensation of water.

18.2 Notes - Cloud Formation

Air Compression and Expansion

- Adiabatic Temperature Changes

- When air is allowed to ______, it ______, and when it is ______, it ______.

- Expansion and Cooling

- ______adiabatic rate is the rate of cooling or heating that applies only to ______air.

- ______adiabatic rate is the rate of adiabatic temperature change in ______air.

Processes That Lift Air

- Four mechanisms that can cause air to rise are ______, ______wedging, ______, and localized ______lifting.

- ______occurs when mountains act as barriers to the flow of air, forcing the air to ascend.

- The air cools adiabatically; ______and ______may result.

Processes That Lift Air

- ______

- A ______is the boundary between two adjoining air masses having contrasting characteristics.

Processes That Lift Air

- ______is when air flows together and rises.

- Localized ______occurs where unequal surface heating causes pockets of air to rise because of their buoyancy.

Stability

- Density Differences

- Stable air tends to remain in its original position, while ______air tends to ______.

- Stability Measurements

- Air stability is determined by measuring the ______of the atmosphere at various heights.

- The rate of change of air temperature with height is called the ______.

Stability

- Degrees of Stability

- A ______occurs in a layer of limited depth in the atmosphere where the temperature increases rather than decreases with height.

- Stability and Daily Weather –

- When ______air is forced above the Earth’s surface, the clouds that form are ______.

- With little vertical thickness compared to their horizontal dimension.

Condensation

- For any form of condensation to occur, the air must be ______.

- Types of Surfaces

- Generally, there must be a ______for water vapor to condense on.

- ______are tiny bits of particulate matter that serve as surfaces on which water vapor condenses when condensation occurs in the air.

Rain and Clouds

1. Watch the video: How Rain is Formed, Clouds are Formed, and Why Clouds are White.

1. Write a paragraph (at least three sentences) explaining why lifting air causes condensation using vocabulary terms from Ch. 18.2.

18.3 Engage Activity

Using the figure on pg. 518-519 fill in the following table

Cloud Type / Height / Typical Weather
Cirrus
Cumulus
Stratus
Cirrocumulus
Altostratus
Stratocumulus
Cumulonimbus
Altocumulus

18.3 Learning Goals

1. Describe how clouds are classified.
2. Compare and contrast clouds and fogs.
3. Explain what must happen for precipitation to form.
4. Identify what controls the type of precipitation that reaches Earth’s surface.

18.3 Notes - Cloud Types and Precipitation

Types of Clouds

- Clouds are classified on the basis of their ______and ______.

- ______(cirrus = ______) are clouds that are high, white, and thin.

- ______(cumulus = a ______) are clouds that consist of rounded individual cloud masses.

- ______(stratus =a ______)are clouds best described as sheets or layers that cover much or all of the sky.

Types of Clouds

- High Clouds

- ______clouds are high, white, and thin.

- ______clouds are flat layers of clouds.

- ______clouds consist of fluffy masses.

- Middle Clouds

- ______clouds are composed of rounded masses that differ from cirrocumulus clouds in that altocumulus clouds are larger and denser.

- ______clouds create a uniform white to gray sheet covering the sky with the sun or moon visible as a bright spot.

- Low Clouds

- ______clouds are best described as sheets or layers that cover much or all of the sky.

- ______clouds have a scalloped bottom that appears as long parallel rolls or broken rounded patches.

- ______clouds are the main precipitation makers.

Types of Clouds

- Clouds of Vertical Development

- Some clouds do not fit into any one of the ______height categories mentioned. Such clouds have their bases in the low height range but often extend into the ______or ______altitudes.

Fog

- ______is defined as a cloud with its base at or very near the ground.

- Fog Caused by ______

- As the air cools, it becomes denser and drains into low areas such as river valleys, where thick fog accumulations may occur.

- Fog Caused by ______

- When cool air moves over warm water, enough moisture may evaporate from the water surface to produce ______.

How Precipitation Forms

- For precipitation to form, cloud droplets must grow in ______by roughly one million times.

- Cold Cloud Precipitation

- The ______process is a theory that relates the formation of precipitation to supercooled clouds, freezing nuclei, and the different saturation levels of ice and liquid water.

- Cold Cloud Precipitation

- ______water is the condition of water droplets that remain in the liquid state at temperatures well below 0oC.

- ______air is the condition of air that is more concentrated than is normally possible under given temperature and pressure conditions.

- Warm Cloud Precipitation

- The ______process is a theory of raindrop formation in warm clouds (above 0oC) in which large cloud droplets collide and join together with smaller droplets to form a raindrop.

Forms of Precipitation

- The type of precipitation that reaches Earth’s surface depends on the ______profile in the lower few kilometers of the atmosphere.

- Rain and Snow

- In meteorology, the term ______means drops of water that fall from a cloud and have a diameter of at least 0.5 mm.

- At very low temperatures (when the moisture content of air is low) light fluffy ______made up of individual six-sided ice crystals forms.

- ______is the fall of clear-to-translucent ice.

- ______is produced in cumulonimbus clouds.

- Hailstones begin as small ______pellets that grow by collecting supercooled water droplets as they fall through a cloud.

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