Thursday, 7 November 2013

Air Pressure, Winds and Temperature

Nov 6th and Nov 7th - Lesson 8
Content: Students will
Energy, light and heat
  • Explain how solar energy affects Earth’s atmosphere and surface (land and water).
    • light → heat
  • Describe the role atmosphere (e.g., clouds, ozone) plays in precipitation, reflecting and filtering light from the Sun, and trapping heat energy emitted from the Earth’s surface.
  • Explain how convection affects weather patterns and climate.
    • light → heat and onshore and offshore winds
    • reflection vs absorption
    • Explain the relationship between differential heating/ convection and the production of winds.
    • Analyze global patterns of atmospheric movements to explain effects on weather.
Today we looked at the demos, the first demo was of air pressure. As you pull the bag out, the pressure inside the jar becomes less. The atmospheric pressure is higher, so it pushes the bag back into the jar.

Then on the second demo we saw that higher temperature = lower pressure.

Then we looked at how we could apply this to the world. What makes the Earth's temperature change is: the ozone layer absorbs sunlight and heats up the Earth. 

Then we looked at how the atmosphere changes, and they key was sunlight. The sunlight is or absorbed or reflected, more is absorbed in the equator, that is why it is hotter.  At the colder areas there is a higher pressure. Pressure moves from high to low. Then we saw that higher pressure has higher density and lower pressure has lower density. The air of the equator will go up. 

Then we looked at a brainPOP because they explained it well. We learned that jet streams were these fast moving strips of air, they can go up to two hundred kilometer per hour. Hurricanes, typhoons, cyclones are the same winds it is just that they are named different.
 We looked at a video that shows the difference in temperature and wind changes. Then we looked at local winds, we drew the local winds. What heated the land and oceans was the sunlight. We did daytime and night time. Water heats up less than land. Higher means lower pressure and lower means higher pressure. When there is higher pressure there is higher density, when there is lower pressure there is lower density. 

Then we made a predictive drawing, what happened on the same beach in the late evening. It is a hard task, we had to use our brains. The ocean stands at a constant temperature. The land temperature changes easily. The land becomes cooler than the ocean. Daytime it is called Sea breeze on shore winds and during night time it is called land breeze offshore winds.

Then we looked at background vocabulary:

Background vocabulary:

the state of the air and atmosphere at a particular time and place: the temperature and other outside conditions (such as rain, cloudiness, wind) at a particular time and place

the average climate; a region with particular weather patterns or conditions; the average weather in a region over years

absorb (v.)
to draw in (heat, light, energy, etc.) ; for this unit we usually mean absorbing solar radiation and it changes to thermal energy

mass divided by volume

differential heating
the uneven warming up of land, ocean or other objects on Earth

displace (v.)
to move (something) so that it is no longer in its original or regular location or position

the lowest region of the atmosphere, extending from the earth's surface to a height of about 6–10 km (the lower boundary of the stratosphere).

a natural movement of air outside often due to differences in air pressure

high pressure
volume of air in lower troposphere that is higher pressure than the surrounding areas

low pressure
volume of air in lower troposphere that is lower pressure than the surrounding areas

 We looked at what causes weather:

“What Causes Weather?

Then we looked at where does the energy from the atmosphere come from:
White things reflect light and dark things absorb light. Clouds are alway light above them. It is always sunny above the clouds. If the light passes through the clouds, it hits land or water. If it is vertical then it tends to absorb if it hits horizontal it tends to reflect.
Where does most of the energy of the atmosphere come from?
It comes from solar energy.  
What happens to the solar energy in the atmosphere?
In the ozone layer, the UV rays are absorbed (changes to heat) so the upper stratosphere is hotter than the lower stratosphere.  
But most of the light goes through the ozone layer.
It could hit clouds or hit the surface of the earth.
If it hits clouds, the light will be absorbed or reflected.  Clouds tend to reflect light back into space.
If hits the surface of the earth, it hits either land or water.
icecaps: light is mostly reflected
brown/yellow: desert, grassland: light is both absorbed and reflected
green/grey/black: absorb a lot of light and reflect some (warm up)
absorbed and reflected, but water is special because it tends to stay a more constant temperature than land

Then we looked at the pressures, what we expected from them:
High Pressure Regions:
Write down the weather associated with high pressure areas.
clear skies, sunny and dry
Low Pressure Regions:
Write down the weather associated with low pressure areas.
rain, cloudy skies

High pressure is good weather, low pressure is bad weather. São Paulo was between high and low pressures, so it can be both. 
To finish off we tried these four questions on our task book to see what we learned:

Complete the following questions in your task book.
  1. What’s the relationship between density and pressure?
  2. What causes wind?
  3. What causes differences in pressure?
  4. When light or UV rays hit something, what can happen to the light or UV rays?

Lastly we went through the answers:

Answer Key

  1. What’s the relationship between density and pressure?

If density is high, pressure tends to be high.  
  1. What causes wind?
Differences in pressure causes wind.  Winds blow from high to low (pressure).  
  1. What causes differences in pressure?
Differential heating of the surface of the earth by sunlight causes difference in pressure.  Higher temperature air above hot land tends to be low pressure.  Cooler air tends to be higher pressure.  
  1. When light or UV rays hit something, what can happen to the light or UV rays?
They either reflect and/or absorb.  Lighter coloured things tend to reflect more light than they absorb.  Darker coloured things tend to absorb more light than they reflect.

1 comment:

  1. Dear Jorge, your post is excellent! You described everything that happened in class. Great job! After checking the other scribe post for this day, you summarized everything that happened in class! I am impressed.

    Something they I found excellent is that you included many great images that help the reader understand what happened in class.

    Keep up the GREAT work,

    Stefano Delmanto


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