1. Monday’s lesson (At the end the lesson you will be able to…) Describe the changes in temperature with height through the lower layers of the atmosphere. Explain what an adiabatic lapse rate is. Explain why and how the SALR is different from the DALR (Lapse rates are often shown in diagram form in exam questions)

2. Environmental lapse rate (ELR)
This is the expected (average) decrease in temperature with height through the lower atmosphere, approximately degrees per 100m.
The ELR varies according to height, time of year, and over different surfaces.

3. Adiabatic means the rising and sinking of air.
So an Adiabatic process is anything that occurs as air rises or sinks.

5. As air rises and cools, the water vapour in the air condenses back into water droplets 

6. When a parcel of air holds the maximum amount of moisture it can it is called saturated.
The point at which a parcel of air is saturated is known as dew point
The altitude at which dew point is reached is known as condensation level

7. orographic uplift

8. Adiabatic lapse rate:
Used to explain what occurs as a parcel of air rises, decreases in pressure and temperature, but increases in volume. The conditions are reversed if a parcel of air moves towards Earth. Adiabatic lapse rates can be either dry (air) or saturated (air)

9. Dry adiabatic lapse rate (DALR):
This is the rate a parcel of air cools at as it rises (or warms if falling) if condensation does not occur. The rate is approximately 1 degree per 100m and is shown on the diagram

11. Saturated Adiabatic Lapse Rate (SALR):
The rate at which air cools if it has risen sufficiently to reach dew point temperature, and condensation occurs. The rate of cooling is slower than the DALR because of the release of latent heat. The SALR varies from 4 degrees per 1000m to 9 degrees per 1000m but the average is 5.5 degrees. The reason for the variation is because of the ability of warmer air to hold more moisture and so it release more latent heat after condensation.

13. When does a parcel of air stop rising?
Air will continue to rise and cool until it reaches the same temperature as the surrounding air. (of course)
This marks the top of cloud development.

15. Stability 1
Stability
This is where a parcel of air rises and cools at a quicker rate than the air surrounding it.
The parcel of air is colder and denser than its surroundings so cannot rise further and sinks.
Condensation and then subsequent rainfall does not occur. Stability is most commonly associated with high pressure and anticyclones.

16. Stability 2 The diagram below shows a graph of stable air conditions: (The DALR lies to the right of the ELR).

17. Instability
Unstable conditions (instability) in the atmosphere exist when a rising parcel of air cools more slowly than the air surrounding it On warm summer day's high levels of insolation can create high surface temperatures. The air above such localised surfaces is then heated by conduction, leading to a high lapse rate. The air rises and cools less quickly than its surroundings. If it remains warmer than its surroundings, the air parcel will continue to rise. If dew point is reached, clouds and thunderstorms will happen

18. We got up to here yesterday!

20. So………unstable air:
Air continues to rise even though it has left the (warm) ground
Vertical currents dominate.
Cumulonimbus clouds and thunderstorms.

21. Summary
SALR:
If rising air is saturated, its temperature falls at about 6 degrees per 1000m. Latent heat is released due to condensation, so decrease is slower.
ELR:
Temperature of air decreases with height at an average rate of 6.5 degrees per 1000m.
DALR:
When a mass of air rises, its temperature decreases adiabatically. The air expands and loses heat energy as it rises and if it is unsaturated, it loses 10 degrees for every 1000m of ascent.

22. FINALLY – 2 MORE

23. Conditional instability
This occurs where the continuation of air rising to form condensation, clouds and precipitation, is conditional on something (for example, mountains and fronts).
The state of instability is based on the air being forced to rise initially. Then it passes over the mountain and returns to stability.

24. Temperature inversions
Temperatures usually decrease with height through the lower atmosphere (troposphere).
A temperature inversion is when the normal conditions are reversed and warm air lies above cold air. It acts to trap air in the lower layers, and can cause the build up of pollutants and smog as in Los Angeles.

25. Weather phenomena associated with local energy budgets (mist, fog, dew, temperature inversions, land and sea breezes).

26. At the end of our third lesson of the week
I will know the three states in which moisture can be found in the atmosphere and understand the terms condensation, evaporation, sublimation, freezing and melting
You will be able to explain the formation of weather phenomena associated with local energy budgets (mist, fog, dew, temperature inversions, land and sea breezes)

27. Key words! - Key words! - Environmental Lapse Rate SALR DALR Stability
Instability
Condensation level
Troposphere
Dew point
Adiabatic
Saturated
Conditional instability*
Temperature inversion*
Environmental Lapse Rate
SALR
DALR
Stability
Instability
Condensation level
Troposphere
Dew point
Adiabatic
Saturated
Conditional instability*
Temperature inversion*

28. Spring Assessment
Draw a labelled diagram to show the ‘night model’ of the radiation balance in the local energy budget. (4)
Describe and explain two ways in which the local energy budget might be different during the day. (4)
What effects does cloud cover have on the earth’s energy budget. (6)