TOPIC: ATMOSPHERE
LEVEL: Intermediate
"It's Windy Up There"
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[information |
preparation |
activity ]
- SCIENCE CONCEPT:
- Convection current is heat transfer from or to something
that can flow. Anything that flows is called a fluid. Fluids
can transfer heat by convection. This movement of the air when
part of it is heated sets up what we call a "convection
current".
- STUDENT OBJECTIVE:
- The student will observe how wind moves in the
atmosphere by constructing a convection current box.
- OVERVIEW:
- In this activity, the student will construct a convection
current box by using an empty aquarium. Students will use
ice to represent cold air and lamps to represent warm air.
Upon lighting a match, this will form a cloud, the warm air
rises as the cool air sinks. Movement is created causing wind.
- TEACHER TEXT:
- As air warms its molecules spread out. When there's some
space between them, the molecules become less dense. This means
the warm air weighs less for the amount of space it is taking up.
The cooler air gets pulled down by gravity because it weighs
more for the amount of space it takes up. It forces the warm
air up. Some of the cooler air at the bottom becomes warmer and
some of the warm air at the top cools. This cool air sinks and
pushes up the warm air. This constant switching is called a natural
convection current.
PREPARATION TIME: 20 minutes
LESSON TIME: 60 minutes
TEACHER PREP:
-
WORDS TO KNOW:
- convection current
- contract
- expand
MATERIALS NEEDED:
- a clean aquarium
- heat lamp bulb
- small bowl of ice
- wax paper
- matches
- STEPS TO FOLLOW:
- 1. Set up the heat lamp shining down in one end of the aquarium.
- 2. Put the bowl of ice at the other end.
- 3. You need to make smoke: roll up some wax paper into a tube
about the size of a pencil. Light one end and let it burn for
a few seconds and then blow it out. It will make quite a bit
of clean smoke.
- 4. Hold the smoldering end of the wax paper in the aquarium near the
bowl ice and observe.
- WHY?
- The air in the warm end of the aquarium will expand and rise. Next,
the cool air at the other end of the aquarium will contract and sink.
The cool air will flow in to replace the sinking cool air. A
circulating wind will develop in the aquarium. The smoke enables
you to see the movement of the air. This is a convection current.
- ASSESSMENT: Can the student communicate what they observed?
- 4....student is able to communicate that warm air rises because it
is less dense and cool air sinks. Cool air moves in to replace warm
air and warm air will move over cool air. A wind is created -
convection current.
- 3....student is able to communicate that warm air rises and cool air
sinks. This sinking and rising causes wind.
- 2....student is able to communicate that a wind was created by the
moving smoke.
- 1....student is able to communicate that warm air rises.