DENSITY CREATES CURRENTS
Focus Questions:
How do changes in density move matter?
How can density drive many of earth’s processes?
Before Reading: Discuss the focus questions with the members of your group. Record any
ideas you might have about this topic.
During Reading: Read the article titled “Density Creates Currents” on pages 48-51 of your
Properties of Matter Student Guide. Think about the focus questions as your read.
After Reading: Complete the paragraph below choosing the most appropriate word from the
word bank to describe how big bird such as vultures and hawks can often be seen gliding around
and around over big parking lots on sunny days without even flapping their wings.
density
increases
warms
rise
convection
dense
expands
sinks
decrease
The reason a big bird is able to glide around and around over big parking lots on sunny days
without even flapping their wings is due to _______. The bird lets itself glide in the rising and
sinking of the air above the parking lot. This movement involves a process called ________.
On a sunny day a black parking lot absorbs heat and _______the air above it. The air becomes
hot and its volume _______. Another word for increases is the air ___________. This causes
the air to become less dense and ______. As the air rises and gets higher from the ground it
starts to cool off. This causes its volume to __________ which causes it to become more
______. When the air becomes more dense, it ________ to the parking lot where it is heated
up again. This process continues and completes a circuit. This is known as a convection current.
The bird never needs to flap its wings because of the continuous motion of the air due to the
changes in density. The bird simply just spreads its wings and glides all day long until the sun is
no longer heating up the parking lot.
Answer the focus questions in your own words: