2.1 Diurnal Energy Budgets

Question 1

What are the tropopause, stratopause and mesopause?

Answer 1

Isothermal layers which mark the upper limit of the troposphere, stratosphere, and mesosphere.

Question 2

What is the role of ozone?

Answer 2

Keeps out harmful UV radiation.

Question 3

What is the role of CO2 in the atmosphere?

Answer 3

Insulation

Question 4

What is insolation?

Answer 4

Incoming solar radiation from the sun. It controls our planet’s climate and weather.

Question 5

As insolation reaches the earth’s atmosphere, what 3 things happen to it?

Answer 5

Reflected (18%), scattered (5%), and absorbed (23%).

Question 6

What are the UV waves from insolation absorbed by?

Answer 6

Ozone, water vapour, CO2, dust and ice particles

Question 7

What is albedo?

Answer 7

The amount of insolation which is reflected back to space by the surface.

Question 8

What are the factors affecting the daytime energy budget?

Answer 8

Insolation
Albedo
Energy absorbed into surface and sub-surface
Long wave terrestrial radiation
Sensible heat transfer
Latent heat transfer

Question 9

What surface reflects the most insolation / has the highest albedo?

Answer 9

Fresh white snow

Question 10

What surface reflects the least insolation / has the lowest albedo?

Answer 10

Dark soil

Question 11

How do clouds affect albedo?

Answer 11

Low-level, thick clouds reflect more insolation than a high-level thin cloud. Thicker clouds have a greater albedo.

Question 12

Why does dirty snow melt faster than fresh snow?

Answer 12

Dirty snow is darker so absorbs more heat energy/insolation.

Question 13

How do the oceans affect albedo?

Answer 13

Still, calm water has a high albedo, while rough, choppy water has a low albedo (light is reflected everywhere).

Question 14

What is long-wave terrestrial radiation?

Answer 14

When short-wave radiation from the sun is absorbed by the earth and re-radiated as long-wave (infrared) radiation because the earth is a cool body. Long-wave radiation is much more easily absorbed by greenhouse gases than short wave radiation.
Clouds absorb long-wave radiation efficiently and re-radiate it back to earth, keeping heat in by the greenhouse effect.

Question 15

What is sensible heat transfer?

Answer 15

Transfer of heat energy by conduction or convection.

Question 16

What is latent heat transfer?

Answer 16

Transfer of heat when water on the Earth’s surface evaporates to water vapour or ice melts to water vapour. The heat needed to make these changes is absorbed from the air, leaving less energy for heating at the surface.
When water vapour condenses it gives out latent heat = latent heat of condensation. This increases the speed and extent of convection.

Question 17

Is air a poor or good conductor of heat?

Answer 17

Poor

Question 18

How does the night-time energy budget differ from the day-time energy budget?

Answer 18

It has no insolation from the sun, and it has no reflected solar radiation. At night the budget is in deficit.

Question 19

What are the factors affecting the night-time energy budget?

Answer 19

Conduction of heat to the surface
Long wave terrestrial radiation
Sensible heat transfer
Latent heat transfer

Question 20

What is the influence of clouds on the night-time energy budget?

Answer 20

A thick cloud cover at night acts as a blanket, keeping the earth and lower atmosphere warm by absorbing and re-radiating terrestrial radiation. The warmer the cloud, the more long wave radiation is re-radiated.

Question 21

When does dew form and why?

Answer 21

It forms after a clear night because on cloudless nights, the earth rapidly loses heat by terrestrial radiation (and cooling is especially intense when the air is calm). When water comes into contact with a cold object whose temperature is below its dew point of the air, the water vapour will condense, releasing latent heat.

Question 22

What is conduction?

Answer 22

Conduction is when the hot ground heats up the air molecules in contact with it, and these molecules pass on the energy to those touching them (only effective in very shallow layer of air).

Question 23

What is convection?

Answer 23

Convection is the upward movement of air as in thermals. The air rises as it is warmer and less dense.

Question 24

How is insolation reflected?

Answer 24

By clouds

Question 25

How is insolation scattered?

Answer 25

By very small particles of dust, air molecules and water vapour

Question 26

How is insolation absorbed?

Answer 26

In troposphere - by water vapour, aerosols and clouds.