Temperatures

[Kiera]

Does anyone know the answer?

This is my daughters science homework.

Why does the temperature of the sea change very slowly compared to that of the air or land temperature changes?

Thanks

[Peter Pedant]

Hi Kiera
I am nost surprised you have typed in the q considering the hard time some of the youngsters get if they type in their home work automatically

what level is she at - sort of beginners ?

If you heat a thing it gets hotter (temp goes up)

H = m s t

(oh god a formula, both you and your daughter are now behind a sofa)

H is the heat put in (cals or J)

m is the mass of the thing heated (kg)

(I am assuming everyone does metric now)

t is the temp defference (deg C)

So far it is easy, for the same amount of heat, if you halve the mass, then the temp will double
and if you ddouble the mass, for the same amount of hear put inm the temp rise will be half

BUT there is the third variable - specific heat

and that of water is very high (lots of heat and only a little temp rise)

and that of air is pretty low (not very much heat leads to a great rise in air temp)

so gasp basically it is tghe difference in s - the specific heat.


NOW when you are writing out her answer for her (hahahaha) remember (I took my O levels in 1966)

that just writing


's'


as the one word answer will not get many marks

and attempting some sort of explanantion see above will score more.

( t is usually written as a greek theta but I can't do that one this computer)

[Kiera]

Thanks, she is in Year 10

[mibn2cweus]

I'm relieved that Peter was able to provide an answer while I worked out mine:

The predominant source of heat on the Earth's surface is provided by the Sun. The Sun produces heat through the process of fusion, changing hydrogen to helium within the extreme heat and pressure that exists within its core. This generated heat migrates to the surface where it travels in the from of light radiated in all directions into space.

For the sunlight reaching Earth the properties of the surface determine what happens to the sunlight that reaches it. Some surfaces are more reflective than others redirecting the sunlight back through the atmosphere and out again into space. The sunlight that is absorbed releases the heat energy it carries into the absorbing material.

Sea water is somewhat transparent allowing some of the sunlight to penetrate below the surface before it is absorbed and releases its heat energy. Once absorbed the mixing of wind and currents also contribute to distributing and dispersing heat further below the surface. This distribution of heat away from the surface reduces the rate at which the surface of the water is heated.

As Peter pointed out, water has a very high heat capacity
An equal volume of water absorbs more heat energy than almost any other material before experiencing the same degree of temperature change.

ocean heat budget

The dispersal of heat and the high heat capacity of water greatly reduce the rate of temperature change at its surface.