Walking down memory lane!

HELLO 403!

I know this is a really late post but yep,here's to recall on one of the topics we did before the holidays:

CLOUDS 

To refresh your memory on what we did on the lesson dated 1st February (Oops),here's a brief summary on what clouds are.

Clouds are formed when air containing water vapour is cooled below a critical temperature called dew point and the resulting moisture condenses into droplets of microscopic dust particles (condensation nuclei) in the atmosphere. The air is normally cooled by expansion during its upward movement (adiabatic cooling). Upward flow of air in the atmosphere may be caused by convection resulting from intense solar heating of the ground; by a cold wedge of air (cold front) near the ground causing a mass of warm air to be forced aloft; or by a mountain range at an angle to the wind. Clouds are occasionally produced by a reduction of pressure aloft or by the mixing of warmer or cooler air currents. 

Cloud formation mechanisms can be anything that causes water vapour to cool and condense which can be achieved through 1) Direct Cooling 2) Lifting of an airmass 3)Buoyant Lifting 4) Mechanical forcing.

Now,what is adiabatic cooling?

Adiabatic Cooling is a form of condensation whereby the air parcel is warmed and rises in pockets as thermals.The parcel of air in the lower atmosphere will compress and warm because it finds itself in a place with higher pressure.However,the parcel of air that is higher in the atmosphere will expand and cool because it finds itself under lower pressure.This process takes place without heat energy entering/leaving the parcel!

You may go to the following website for an animation on adiabatic processes:

http://www.wiley.com/college/strahler/0471480533/animations/ch06_animations/animation1.html

After learning the concepts,here's a recollection of what we did for the lesson @amphi :)

Materials:

1. Bottle (With cap)

2. Hot water

3. Matches

Procedure:

1. Add some hot water into the bottle

2. Shake it ensuring that the bottle is "coated" with the hot water

3. Pour out the water in the bottle

4. Quickly cap the bottle

5. Light a match

6. Blow to extinguish it and quickly place the match into the bottle,enabling the smoke to enter

7. Cap the bottle

8. Apply pressure on the bottle by squeezing and crushing it.

9. Remove the cap

10. Squeeze the bottle over a piece of black paper to see "clouds" emerging!

Yup,to conclude this blog post.Here's the hyperlink to similar experiments as the one we did in class!Enjoy :D

- http://www.youtube.com/watch?v=E8AvfXar9zs&feature=related

- http://www.youtube.com/watch?v=HIZq2gXBsHU&feature=related

Peace.

Glenda (05)