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3 Express Pure Geog:Weather and Climate7th March 2012Elements of Weather: Relative Humidity

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2+Concerns of Previous Lessons: Website Can we download the slides?

Yes. www.armanalluwie.blogspot.com

3+Concerns of Previous Lessons:Latitude/ Longitude/ Altitude Latitude / Longitude / Altitude

geographic coordinates used to specify a location in relation to another

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imagine the earth as a sphere

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0°

90° North (+90°)

90° South (-90°)

Latitude

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5+Longitude

0° Prime Meridian

6+

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0°

90° North (+90°)

90° South (-90°)

Latitude

0° Prime Meridian

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7+Altitude

Since the Earth is not flat, we need the third axis to measure elevation (height)

whiteboard

8+Concerns of Previous Lesson:Maritime Effect

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Water Bodies

Concept: Water bodies heats up and cools down slower

Land bodies

S L O W E R

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Concerns of Previous Lesson:Mistakes Cooler Summers

Air over water bodies heat up slowly

Warmer Winters Air over water bodies

lose heat slowly

eg. San Diego

Warmer Summers Air over land bodies

heat up faster

Cooler Winters Air over water bodies

lose heat slowly

Eg. Winnipeg

Coastal Areas Non- Coastal Areas*

*areas deep within the continent

maritime effect continental effect

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Temperature:Distance from the Sea

Cooler Summers Air over water bodies

heat up slowly

Warmer Winters Air over water bodies

lose heat slowly

eg. San Diego

Warmer Summers Air over land bodies

heat up faster

Cooler Winters Air over land bodies

lose heat faster

Eg. Winnipeg

Coastal Areas Non- Coastal Areas*

*areas deep within the continent

maritime effect continental effect

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11+Temperature:Cloud Cover

earth’s surface

temperature rises up quickly

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12+Temperature:Cloud Cover

earth’s surface

heat escapes easily

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13+Temperature:Cloud Cover

earth’s surface

reflects part of theincoming solar radiation

reflects back heatto the ground

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14+Temperature:Cloud Cover

earth’s surface

reflects back heatto the ground

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Temperature:Cloud Cover

More cloud cover Smaller difference in

day and night temperatures

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16+Lesson objectives

By the end of the lesson, we will be able to explain how evaporation, condensation, precipitation

and saturation affect relative humidity

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17+Humidity

amount of water vapour present in the air

places near the equator have high humidity large amount of water vapour in the air

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18+Relative Humidity

proportion of water vapor present in the air, in relation to the maximum amount the air can hold1 at particular temperature

expressed as %

1hold: contain100 -

50 -

25 -

relative humidity = 50 %

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100 -

50 -

25 -

100 -50 -25 -

change in temperature

relative humidity = 50 %

same amount of water vapour

relative humidity= ?

Relative Humidity

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100 - 50 -

change in temperature

same amount of water vapour

relative humidity > 100%

100 -50 -25 -

same amount of water vapour

relative humidity= 100%

beyond saturation point

Relative Humidity

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21+Relative Humidity

http://www.youtube.com/watch?v=CL5cgXwKUXc

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22+Relative Humidity

Recall, what is meant by “saturation”? air is carrying the maximum amount of water vapor it

can hold at that temperature

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23+Relative Humidity:Changes in Holding Capacity

6000

0 sea level

2000

4000

temperature changeswith increasing altitude

m

24+Relative Humidity:Changes in Water Vapour

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land surface large lakes/ oceans

wind directionair parcel

more water vapour

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25+Revisiting The Water Cycle

http://www.youtube.com/watch?v=AQKdkponoZM

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27+Relative Humidity:Precipitation Definition: water falling from the atmosphere onto

the Earth’s surface

form depends on the temperature of the place where it falls

Liquid Freezing Frozen

Drizzle Freezing Drizzle Snow

Rain Freezing Rain Hail

Ice Crystals

precipitation ≠ rain

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28+Relative Humidity:Cloud Formation

http://www.youtube.com/watch?v=SKmLEgUivj4

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29+Relative Humidity:Relation to Cloud Formation In pairs, name the processes shown in the video

Condensation/ Evaporation/ Precipitation/ Saturation

Explain each process and describe how the relative humidity changes at each stage of the process

Submit your worksheets to Mr. Arman

10 minutes

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30+Lesson objectives

Are we able to explain how evaporation, condensation, precipitation

and saturation affect relative humidity?