1. Introduction To Weather Dynamics

2. Introduction to Weather - Video

3. What you will learn… In this unit, you will…
Describe Earth’s energy budget
Explain how energy is transferred between and among land, air and water
Describe weather-related properties of the atmosphere such as pressure and humidity
Explain how areas of high and low pressure move air and energy around the globe

4. Meteorology
The study of
the Earth’s
atmosphere
and weather
systems.

5. The day to day changes in the
Weather (page 10)
The day to day changes in the
atmosphere
at a particular
location
on Earth.

6. long-lasting and recurring conditions of the
Climate A
widespread,
long-lasting and recurring conditions of the
atmosphere.

7. Weather – What is it?

8. Components of Weather (see Table 1.1, page 11)
Temperature
Coolness or warmth of an object (average of kinetic energy – oC)
Precipitation
Any form of water that falls to Earth from atmosphere (mm or cm)
Atmospheric Pressure
The force of the atmosphere per square meter of surface below it (kPa)
Humidity
The amount of water vapor in the air (%)
Wind Speed & Direction
How quickly the air moves and its direction (km/h; NSEW bearings)
Sky Cover
The portion of sky that is covered by clouds

9. Sheet to complete: Part A
To do: p. 4, #4 & 6

10. Earth’s Energy Budget (page 13)

11. Types of Energy Transfer - Radiation
Energy is transmitted as photons (electromagnetic radiation)
Think: The Sun!

12. Solar Radiation
Solar constant is defined as the amount of radiant energy that hits one square meter of the Earth’s outer atmosphere every second (1362 J/s/m2)
Unit of energy → Joule (J)
See Figure 1.4, page 14

13. Greenhouse Effect – the warming of Earth as a result of greenhouse gases (CO2, water), which trap some of the energy that would otherwise leave Earth

14. Terrestrial Radiation
Earth would constantly increase in temperature if it did not radiate energy back to space.
It would take approximately 25 years for the oceans to boil if no energy was emitted back to space
Terrestrial Radiation is composed primarily of infrared photons (light)

15. Incoming and Outgoing Radiation
About 49% of the solar energy that enters Earth’s atmosphere is absorbed by the land and ocean.
About 42% is absorbed, reflected, and scattered by clouds, gases, and aerosols in the atmosphere.
About 9 percent is reflected by Earth’s surface.
Figure 1.4

16. Solar Radiation Arriving at Earth’s Surface (see Figure 1.4, page 14)

17. Sheet to complete – Part B

18. Factors Affecting Absorption of Energy
1. The colour of a surface:
Which one reflects more light?
Snow or a farmer’s field?
Albedo - the reflectivity of a surface
Field in the summer – 20%
Field covered with snow – 70 or 80%

19. Factors Affecting Absorption of Energy
2. The nature of a substance: Different substances absorb energy at different rates.
Which one will warm up more quickly? Water or sand?
The Specific Heat Capacity of a substance determines how much and how quickly it absorbs and releases energy.
Water has a much higher specific heat capacity than land and air do.

20. Specific Heat Capacity
Substance
Specific Heat Capacity at 25oC (J/kg/oC)
Water
4186
Air
1020
Iron
444
Copper
385
Sand
290
Gold
129

21. Heat Sinks
Because the specific heat capacity of water is higher than that of land, water is considered to be a better heat sink.
Heat Sink: any substance that can absorb and retain energy without changing state.

22. Water is a good heat sink
Because there is so much water on Earth, and water is such a good heat sink, water has a great influence on weather.
Is it colder in the winter in Saskatoon or Halifax?
Is it colder in the summer in Saskatoon or Halifax?
Figure 1.5

23. Weather!
The energy transformations that happen between the time solar radiation is absorbed and the time it is re-emitted are what drive weather systems.

24. Practice sheet – Part C
Questions – p. 15, 1-4
Answers

25. Thermal Energy Transfer
Thermal Energy – Energy created by the movement of particles in a substance.
Heat: Thermal energy that is transferred from one object to another

26. There are three types of heat transfer…
Conduction
Convection
Radiation

27. Types of Energy Transfer - Conduction
Requires contact between atoms; more energetic atoms collide with more energetic atoms and energy is transferred (solids with solids)
Example: Warming a pot on a stove

28. Types of Energy Transfer - Convection
In a gas or liquid, atoms are free to move and as they warm they become less dense and rise. Atoms that are cold and denser will then descend and create a convection current.
(liquids/gas)

29. Types of Energy Transfer - Radiation
Energy is transmitted as photons (electromagnetic radiation)
Think: The Sun!

30. Definitions – Conduction, Convection and Radiation
Video – Radiation , Conduction and Convection
Draw – p. 17, fig. 1.7

31. Atmospheric Pressure
Atmospheric Pressure – the pressure exerted by air on its surroundings due to the weight of the air
Measured in kilopascals (kPa)
At sea level, the atmospheric pressure is kPa (or 1 kg/cm3)

33. Three factors that can reduce atmospheric pressure:
Altitude – The higher you go, the pressure decreases
Temperature – When warm air pushes into a cold air mass, pressure decreases. When cold air pushes into a region of warm air, the atmospheric pressure in that location increases.
Humidity – The more water vapour in the atmosphere, the more the air is light (so more humidity = less pressure)

34. Video – Atmospheric Pressure

35. Layers of the Atmosphere
See Figure 1.8, page 19

37. Layers of the Atmosphere Layers of the Atmosphere
Troposphere
All water vapour is present here
All weather occurs here
From surface to ~10km
Temperature ranges from -50°C to 50°C
Stratosphere
Ozone is present here
From 10km-50km
Temperature ranges -50°C to -30°C

38. Layers of the Atmosphere
Mesosphere
Meteorites burn up here
Some ions are present here
From 50km to 90km
Temperature ranges from -30°C to -90°C
Thermosphere
Aurora present
From 90km to 180km (space)
Temperature ranges from -90°C to over 200°C

40. Layers of the Atmosphere

41. Video – Layers of the atmosphere

42. To do:
Finish worksheet:
Answers