Home » Ask & Discuss » Physics. » Thermal Physics « Back to Discussion

Thermal Physics

Cool goIITian

Joined:	27 Nov 2008
Post:	54

10 Feb 2009 16:31:21 IST

0 People liked this

315

dbt concept

None

why do lakes freeze from top to bottom.

Share this article on:

Comments (3)

Debotosh Chatterjee

Blazing goIITian

Joined: 11 Sep 2008

Posts: 1159

10 Feb 2009 23:26:52 IST

Like 0 people liked this

because ice is a bad conductor of heat............once it is formed on the top layer it conserves heat and keeps the lower layers unfrozen!!!!!!!!!!!!!!

siddharth raghuraman

Cool goIITian

Joined: 28 Dec 2007

Posts: 76

10 Feb 2009 23:59:48 IST

Like 1 people liked this

water has the max density at 4 degs... obviusly denser substances tend to go down compared to rarer (les dense in comparision) substances.. so frm abt normal cold temps..say around 10 degs ...when water cools down it tends to 'sink'..it dusn sink but due to convektion curents..the coold water goes down and water which is rares come up... this way it continues till the whole pond is at 4degs.. after that.. the convektion stops..and on further cooling..no doubt tht the density deks as still temp dec..even the water dusn move also now that its rarer than the 4 degree water... so the top layer freezes... and since ice is a bad conduktor..it prevents the quick freezing of lower layers(in comp with the tym taken for the uper layers to freeze after the whole pond is at 4degs) so it apears it freezes frm top to bottom...

Sagar Saxena

Forum Expert

Joined: 8 Oct 2008

Posts: 7221

11 Feb 2009 01:21:35 IST

Like 1 people liked this

the reason can be:

ice is less denser than the water and thus ice floats and ice is insulator ..............this can be reason why it freezes from top to bottom

Quick Reply

Reply

	Some HTML allowed.
	Keep your comments above the belt or risk having them deleted.
	Signup for a avatar to have your pictures show up by your comment
	If Members see a thread that violates the Posting Rules, bring it to the attention of the Moderator Team