1. What is Weather?

2. Combination of properties of the troposphere at a given time

3. Includes….. Temperature Pressure Humidity Precipitation Sunshine
Cloud cover
Wind direction & speed

4. Air Mass  a section of air that has the same properties (temp & humidity)

5. Front boundary between
two air masses
Warm front – when a warmer air mass replaces a cooler one
Cold front – when a cooler air mass replaces a warmer one

6. Why is precipitation normally found along fronts?
1. Front = rising air
2. Rising air = cooling air
3. Cooling air = lower ability to hold H2O

7. As the air cools, it cannot hold as much water vapor, so the water vapor condenses to clouds and eventually precipitation

8. Air Pressure - weight of the atmosphere per unit area
- gravity has a huge affect on air pressure
(pressure is near Earth’s surface)

9. HIGH pressure areas form when cooler, more dense air sinks towards Earth’s surface.
The air warms as it sinks so Highs are usually associated with fair or clear weather.

10. LOW pressure areas form when warmer, less dense air rises into the atmosphere.
Usually associated with fronts and precipitation because of the rising air

13. Why uneven heating? Winds result from the uneven
heating of the atmosphere
Why uneven heating?

14. 1. Specific heat of land (soil) and water
land and sea breezes

16. Describe wind direction using High and Low
Describe wind direction sinking air and rising air
Land Breeze --- air is sinking over land because it cools more quickly when the sun goes down, H over the land and L over the water.
Sea Breeze air is rising over the land because it heats more quickly in the daytime

18. 2.

19. Uneven heating from the sun helps form pressure belts around Earth
These pressure belts contribute to the production of three major convection zones in the atmosphere
Label pressure belts, discuss why equator is L
Equator is L because it receives the most direct sunlight = lots of heating = rising air = low pressure area……
Air cannot rise forever, it will eventually have to sink, this is why the 30N and 30S are H pressure belts = sinking air…. (for this reason, many of the worlds largest deserts are found at this latitude)
60N and 60S are L pressure belts
90S and 90N are H pressure belts

20. Add winds to the diagram…. Without coriolis…
Add winds to the diagram…. Without coriolis….. This would be accurate BUT Earth rotates

21. Coriolis Effect

22. Draw winds with coriolis effect LABEL!!!

23. Hadley Cell animation

24. Climate Average long term weather of an area 2 Main factors
Temperature
Precipitation

25. Temperature & Precipitation are affect by four main factors…..

26. 1. Latitude – determines the amount of solar energy a region receives
Only the equator receives direct sunlight year round

27. Earth’s tilt gives us seasons NOT distance from the sun

28. 2. Atmospheric Circulation
Convection currents and prevailing winds created by the heating and cooling of the atmosphere

30. 3. Ocean Circulation
Also affected by solar heating and the Coriolis Effect.

31. Oceans have a great affect on climate b/c H2O holds a lot of heat
Oceans/Large bodies of H2O tend to make climates more moderate
* Warmer winters & cooler summers than
inland areas
* Usually more precipitation

34. 4. Topography - shape of the land

35. What is El Nino?

36. Normal South Pacific Conditions

37. Upwelling of nutrient rich water provides lots of food for fish

38. Surface winds
blow westward
EQUATOR
Warm waters
pushed westward
SOUTH
AMERICA
AUSTRALIA
Warm water
Thermocline
Cold water
Normal Conditions

39. During non-El Niño/normal years, the southeast trade winds, drag surface water westward away from shore. As surface water moves away, upwelling brings up colder waters from depths of meters or more. This deep sea water is rich in nutrients which can sustain large fish populations.

40. El Nino (ENSO – El Nino Southern Oscillation)

41. Prentice Hall Textbook animation link

42. Winds weaken,
causing updrafts
and storms
Drought in
Australia and
Southeast Asia
EQUATOR
Warm water
flow stopped
or reversed
AUSTRALIA
SOUTH
AMERICA
Warm water deepens off
South America
Warm water
Thermocline
Cold water
El Niño Conditions

43. During an El Niño event, the southeast trade winds weaken and so does the amount upwelling in the eastern Pacific.
The deeper thermocline means that any upwelling that does occur is unable to tap into the rich nutrients found in deeper waters. Consequently, warm nutrient-poor water predominates the region and a decrease in the fish population is observed.