This
week we have been learning about Whale migration. We've found out that
Humpback Whales spend much of the year in the Southern Ocean around
Antarctica, feeding on krill and other zooplanktons. Then, they migrate
up past New Zealand to the warm tropical waters of the equator to give
birth to baby whales. They stay in the warm waters until the baby whale
(called a 'calf') is fat enough with BLUBBER (word of the week!) to
survive the cold waters, before migrating back to Antarctic waters.
Mr Dobson was wondering though, if Antarctic waters are so cold....
...why doesn't the Antarctic Ocean just freeze?
To find out why, Room SEven conducted an experiment using ice.
First,
we measured the temperature of ordinary, fresh water ice. We found that
it was close to, or exactly, 0 degrees celcius. This is the temperature
that fresh water freezes.
We then added water and salt to the ice to make a salty water solution and continued to take temperature measurements.
The temperature DROPPED even more! Some groups reported temperatures of minus 10, 12 and even -13 degrees!!!
We concluded that, although fresh water freezes at 0 degrees celcuis, salt water freezes at a MUCH lower temperature.
So that's why the ocean around Antarctica isn't frozen solid!
No comments:
Post a Comment