2.1 Diurnal energy budgets

Question 1

What are the different layers of the atmosphere?

Answer 1

bottom to top:
True troposphere
tropopause
Scientists stratosphere
stratopause
Make Mesosphere
mesopause
Theories Thermosphere

Question 2

What causes the northern lights?

Answer 2

friction with the thermosphere and solar winds

Question 3

What effects incoming solar radiation

Answer 3

1. the solar constant - energy released by sun
2. distance of Earth from sun - not constant due to orbital rotation, can cause 6% variance
3. altitude of the sun: depends on angles of Earth’s surface that is falling on - same amount of solar radiation above 60degrees north/south of equator has to cover twice land surface to equator
4. length of night and day: long period of time where areas north of artic circle and south of antarctic circle do not receive any incoming solar radiation

• around 5% is scattered by atmosphere
• 24% reflected into space (18% by white upper surface of clous and water droplets in them and 6% by Earth’s surface mainly by snow)
• 23% absorbed by atmospheric gases (mainly ozone and O2 at high levels, small amounts by CO2 and H20 near earths surface)
• 48% absorbed by Earth’s surface and heats it

Question 4

What is albedo?

Answer 4

• proportion of energy that is reflected back to the atmosphere
• lighter materials have a higher albedo value and therefore Reflect more radiation energy
• darker surfaces absorb more

Question 5

What is planetary albedo?

Answer 5

proportion of insolation scattered and returned to space by Earth

Question 6

What effects surface/subsurface absorption?

Answer 6

• large bodies of water and snow cover which can have high albedo and reflect as much as 80-90% of incoming radiation
• some of incoming energy will be transferred from surface into sub-surface soil by conduction
• light-coloured soil is poor conductor so heating mainly confined to surface (hence deserts hot in day)
• dark volcanic soil or rocks with low albedos of 5-10% will absorb heat well
• moisture content:
• coarse sandy soil that has large pore spaces be a poor conductor of heat, so heat concentrate on surface
• whereas soil with high water content will conduct heat down into sub-surface so soil surface cooler

Question 7

Long wave radiation

Answer 7

• Earth is a cold body so it EMITS longwave radiation back to space
• it is easily absorbed by greenhouse gases/cloud - greenhouse effect
• heat loss is greatest on cloudless nights

Question 8

What is sensible heat transfer?

Answer 8

• occurs when heat transferred by direct conduction/convection
• refers to energy transfer between surface and a fluid that is in contact with it that results in a temperature change in a substance without it changing state

Question 9

What is latent heat transfer?

Answer 9

• occurs when water evaporates to water vapour, or ice melts into water vapour.
• Heat required to change state is absorbed from the air, leaving less energy to heat the surface.
• Latent heat of condensation increases the speed and extent of convection.

Question 10

When does dew form?

Answer 10

• water saturated air comes into contact with an object with a temperature cooler than the airs dew point.
• Water vapour condenses into liquid form.
• Latent heat is released during condensation, adding heat to the ground

Question 10

Example of latent heat transfer - Evaporation

Answer 10

• water molecules gain enough energy from surrounding air to change state to a gas, and leave the surface.
• This leaves overall energy less at the surface, so the surface and air cool.

Question 11

How is absorbed energy returned to earth?

Answer 11

greenhouse gases absorb reradiated longwave radiation and atmosphere warms.

Question 12

How do clouds effect incoming radiation?

Answer 12

- reflection
- absorption
- scattering
- Daytime:
-Thick, low-altitude clouds like cumulus or stratus clouds tend to have a strong cooling effect because they reflect a lot of solar radiation.
- However,thin high-altitude clouds like cirrus clouds can allow more sunlight to pass through while still trapping some outgoing infrared radiation, potentially leading to a net warming effect.

• Nighttime: Clouds generally have a warming effect at night because they trap outgoing longwave radiation emitted by the Earth’s surface, reducing nighttime cooling.

Question 13

What is insolation?

Answer 13

radiation from the sun reaching the earth over given time

Question 14

What surface temperature changes occur?

Answer 14

• during the day, the surface is heated by radiation, conduction, and convection.
• Surface air moves slow due to friction, is heated, and rises as a result of convection.
• At night, ground is cooled by lack of radiation, heat from soil and rocks rises to heat the surface.

Question 15

What is sensible heat transfer?

Answer 15

• heat energy that is transferred by convection or direct conduction

Convection: thin air layer heated above surface (poor conductor), molecules vibrate more, gas less dense so rises, air cools, becomes denser and falls, to replace rising air. At night, air might sink in higher latitudes.

Conduction: heat transfer between ground/air when they are in contact

Question 16

What is latent heat transfer?

Answer 16

• heat which is transferred during a change in state

Question 17

What are the examples of latent heat transfers in the energy budget?

Answer 17

• Evaporation: water molecules gain enough energy from surrounding air to change state to a gas, and leave the surface. This leaves overall less energy at the surface, so the surface and air cool.

Dew: water saturated air comes into contact with an object with a temperature cooler than the airs dew point. Water vapour condenses into liquid form. Latent heat is released during condensation, adding heat to the ground.

Absorbed Energy returned to Earth: greenhouse gasses absorb reradiated longwave radiation and atmosphere warms.