Physical-Lecture3

Question 1

Global Heat Budget

Answer 1

Without greenhouse gases Earth’s surface temperature would. be ~-18degC. The actual average temperature of Earth’s surface is ~14degC and due to energy recycling within the atmosphere by greenhouse gases Reflected sunlight = 30%. Heat emitted 70%. 0.0008%Internal heat sources.

Question 2

Variation in heat budget

Answer 2

net solar gain at equator. (smaller solar footprint). Higher angle of incidence in the higher latitudes.

Question 3

Why do all latitudes on the earth radiate similar heat back into space.

Answer 3

Thermal radiation is a function of the temperature of the object.Heat radiated at the latitude of Arctic ice is about 65%of heat radiated at thelatitudeof the coral sea.

Question 4

Heat Balance

Answer 4

In steady state, heat input from sun must be balanced by heat lost by atm./
ocean/land. Since more heat comes in in the tropics than at the poles, and more
heat is lost at higher latitudes, there must be transport of heat from the tropics
to higher latitudes, in the atmosphere and ocean. (Land can’t transport heat

Question 5

Air and Heat

Answer 5

Apart from the outermost atmosphere, only the Earth’s surface is heated by the Sun, so it is hotter than the atmosphere above. Heat moves from hot to
cold so is transferred upwards. In the lower 10km of the atmosphere (the troposphere), the air temperature typically decreases upwards at a rate of 6.5/km

Question 6

Water and heat

Answer 6

Higher temperature water contains more heat; heat is a form of
energy
Adding or taking away heat from water can (i) increase or decrease
the temperature of liquid water or (ii) keep the temperature the same
but make it evaporate or freeze.
Evaporation and ice melting (i.e. phase or state changes) involve much
more heat energy than just raising the temperature of liquid water.