Water in the Air Chapter 16 section 1

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Water in the AirChapter 16 section 1

• S6E3.b. Relate various atmospheric conditions
  to stages of the water cycle.

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Water in the Air

• I. Water Cycle
• A. the continuous movement of water from Earths
  oceans and rivers into the atmosphere, into the
  ground, and back into the oceans and rivers.

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• II. Humidity
• A. Humidity info
• 1. airs ability to hold water vapor changes as
  air
• temperature changes.
• B. Relative Humidity
• 1. given as a percentage
• 2. when air holds all the water it can -
  saturated
• 3. relative humidity 100 - fully saturated
• 4. actual water vapor content X 100 relative
  humidity ()
• saturation water vapor content

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• C. Factors affecting Relative Humidity
• 1. two factors, water vapor and temperature
• a. relative humidity decreases as the
  temp.
• rises and increases as the temp.
  drops
• D. Measuring Relative Humidity
• 1. instrument used - psychrometer
• a. two thermometers, wet-bulb (covered
  with a cloth) and
  dry-bulb
• b. difference in temp readings between the
  thermometers indicates the
  amount of water vapor in the
  air, larger difference,
  less water vapor, lower humidity.

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• III. Condensation
• A. Condensation info
• 1. before condensation can occur the air must
  be saturated, relative humidity of 100.
• B. Dew Point
• 1. the temp at which a gas condenses into a
  liquid
• 2. air is saturated
• 3. must have a surface to condense on.

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• V. Precipitation
• A. Rain
• 1. water drops in the cloud become a
  certain size they will fall.
• B. Sleet and Snow
• 1. sleet forms when rain falls through a layer
  of freezing air.
• 2. snow forms when temp are so cold that water
  vapor changes directly to a solid.
• C. Hail
• 1. balls or lumps of ice
• 2. forms in cumulonimbus clouds
• 3. updrafts of air carry raindrops high in
  the clouds, raindrops freezes, as it falls it
  is uplifted again high in the clouds (can
  happen many times), when the hail is too heavy
  it falls to the ground.

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Review

• 1. If an air mass is cooled and the amount of
  humidity in the air mass stays the same, does the
  relative humidity of the air mass increase or
  decrease?
• Answer it increases
• 2. What causes dew?
• Answer at night and in the early morning, the
  air cools and can hold less moisture. Dew is the
  water that condenses from the air in the early
  morning.
• 3. How does hail form?
• Answer when raindrops are carried to the tops of
  clouds by updrafts. The raindrops freeze and
  become hail. The hail grows larger as it is
  repeatedly covered with layers of freezing water
  from updrafts.
• 4. What does a relative humidity of 75 mean?
• Answer the air contains 75 of the maximum
  amount of water that the air can hold at a given
  temperature.

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• 5. What happens to relative humidity as the air
  temperature drops below the dew point?
• Answer as the air temperature drops below the
  dew point, relative humidity increases to the
  saturation point and condensation occurs.
• 6. Which cloud is most likely to produce light to
  heavy, continuous rain?
• Answer nimbostratus cloud
• 7. What is the relative humidity of air at its
  dew point?
• Answer 100
• 8. Which of the following is NOT a type of
  condensation?
• a. fog b. cloud c. snow
  d. dew