Unit 6: Atmospheric Science

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Unit 6 Atmospheric Science

• Topics
• 1. Review Energy Transfer
• 2. Dew Point Humidity
• 3. Energy at the Earths surface

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Review

• What is the name of the radiation that we receive
  from the sun? How about the Earth?
• What are the 3 forms of energy transfer?
• What is the wavelength of UV rays?
• What waves do waves do we get from the sun? How
  about the Earth?

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Dew Point and Humidity

• The dew point is the air temperature at which
  condensation occurs
• Condensation is the process of water vapor
  turning into liquid water.
• The humidity is the percentage of water vapor in
  a parcel of air
• A parcel is just a portion/section of the air

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How does dew form?

• It is a relationship between the amount of
  humidity and the temperature

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Time- 2 Pm Temp- 80
Time- 7AM Temp.- 55
Time- 6 PM Temp- 68
Time- 8 PM Temp- 55
Dew droplets
D.P.- 55 Humidity- 45
D.P.- 55 Humidity- 70
Dew Point- 55 Humidity- 100
D.P.- 55 Humidity-100
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Dew Point versus Humidity

• The dew point is not only on the ground it is
  also up in the sky
• As you go higher in the sky the temperature cools
  to the dew point and condensation occursCLOUDS

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Cloud Formation
Expands as condenses due to thinner air
Dew Point breached
Rising air cools to the dew point
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Humidity

• The Relative Humidity is the percentage of water
  vapor in a parcel of air.
• According to the previous diagrams, what time of
  day is the relative humidity the highest?
• Early morning and late evening
• Is there any difference between 80 humidity in
  the summer and winter?

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Mr. Bacciles Demonstration

• When the air is heated it expands. Therefore,
  there is more room to fit water vapor. So 80
  humidity in the summer is actually much more
  water vapor in the air.

summer
winter
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Figuring Dew Point and Humidity

• A sling-psychrometer is the tool used for
  figuring this
• There is a wet-bulb and a dry-bulb on the tool
• The wet-bulb measures the amount of moisture in
  the air.
• How does this work?

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The Wet-bulb

• The same reason why you feel cool after swimming
  in the summer
• If the air is dry, then there is a lot of room
  for water vapor in the air.
• Therefore, the water on your skin will evaporate
  quickly into the air
• Evaporation is cools its surroundings, therefore
  your skin feels colder

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• Clear Skies very little moisture in the air
  more room in the air for evaporation cooler
  skin (wet-bulb)
• This will cause a big difference between the
  wet-bulb and dry-bulb

• Cloudy Skies lots of moisture in the air less
  room in the air for evaporation less change in
  temp. (wet-bulb)
• This will cause a Small difference between the
  wet-bulb and dry-bulb

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The Wet-Bulb cont.

• The wet-bulb works the same way. When you spin
  it, the dry bulb reads the air temperature and
  the wet-bulb reads the moisture
• If the air is dry, there will be a big difference
  between the two temperatures
• If the air is very moist, then both will be
  similar

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Using the E.S.R.T.

• If the dry-bulb temperature is 20 degrees and the
  wet-bulb is 15 degrees, what is the dew point and
  humidity.
• First take difference between the wet-bulb and
  dry bulb 5 degrees
• Now, use the difference number 5 and the dry bulb
  temperature 20

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Energy at the Earths surface

• Energy interacts at the Earths surface in many
  ways
• It reflects (bounces off), refracts (bends),
  scatters (like reflection but in all directions),
  absorbs (soaks in) and radiates (gives off)
• It is important to remember if an object is a
  good radiator then it is also a good absorber

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REFLECTION

• Electromagnetic energy bounces off a medium
• The surface needs to be light in color and
  flat!!!
• The angle of incidents needs to match the angle
  of reflectionlet me show you

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ANGLE OF INCIDENTS
ANGLE OF REFLECTION
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ABSORPTION

• When the radiation is soaked into the ground like
  a sponge it is absorbed
• The best surface for this is dark colors and
  rough surfaces!!!!
• It is very important to remember if a surface
  absorbs energy fast, it will also radiate it fast
  (if something warms fast then it cools fast)