1. Chapter 17.1 Atmospheric Characteristics

2. What is Weather?
Weather is constantly changing, and it refers to the state of the atmosphere at any given time and place.
Climate, however, is based on observations of weather that have been collected over many years. Climate helps describe a place or region.

3. Is this map an example of weather or climate?

4. Composition of the Atmosphere
Air is a mixture of different gases and particles, each with its own physical properties
Carbon dioxide is present in very small amounts but plays a significant role in heating the atmosphere because:
It absorbs heat given off by Earth. It also absorbs some solar energy.

5. What is the most abundant gas in Earth’s atmosphere?
Is this gas important meteorologically?

6. What is the most abundant gas in Earth’s atmosphere? Nitrogen
Is this gas important meteorologically? NO

7. Minor Components of the Atmosphere
Water Vapor
Varies from none to about 4%
It is the source of all clouds and precipitation
It is important because it absorbs heat given off from Earth’s surface. It also absorbs incoming solar energy

8. Minor Components of the Atmosphere cont.
Latent Heat
This is the term used to describe the heat energy that is released when water vapor changes from one state to another. (freezing, melting, condensation, etc.)

9. Latent heat is the energy source that drives weather, especially severe weather.

11. Which phase changes absorb energy?
Which phase changes release energy?

12. Which phase changes absorb energy? Melting and evaporation
Which phase changes release energy?
Condensation and freezing

13. Minor components: continued
Particles – also known as: Aerosols
From both man-made and natural sources
Examples include emissions from vehicles

14. These particles (aerosols) are important as they act as the surface for water vapor to condense, forming clouds

15. These particles can absorb or reflect incoming solar radiation
They also contribute to varied hues of red and orange sunrises and sunsets.

16. What is the importance of aerosols to weather?

17. The particles provide a solid surface for water vapor to condense on (condensation nuclei)
They absorb and reflect solar radiation, which can change temperatures. . . Followed by changes in weather

18. Ozone A form of oxygen that combines Three oxygen molecules O3
Not the same oxygen as we breathe (O2)
There is very little ozone in the atmosphere, distributed unevenly, between 10 & 50 Km
Ozone is concentrated in the stratosphere
At this altitude oxygen molecules are split into single atoms of oxygen

19. The ozone layer is crucial to life on Earth
The ozone layer is crucial to life on Earth. Ozone absorbs potentially harmful
UV radiation from the Sun

20. Why is the ozone layer important to all life forms on Earth?

21. Ozone protects all living things by filtering our a large portion of the dangerous Ultra Violet rays
Without ozone we would not be able to stay outside exposed to the Sun for very long before it could cause severe burns

22. Human influence
Primary pollutants are emitted directly from identifiable sources
Emissions from transportation vehicles account for nearly half of the primary pollutants by weight

23. Human Influence cont.
Secondary pollutants are not emitted directly into air. The form in the atmosphere when reactions take place between primary pollutants and other substances
This noxious mixture is called photochemical smog

25. Height and Structure of the Atmosphere
As you travel away from Earth there are fewer and fewer molecules.
Atmospheric pressure is the weight of the air above
The average air pressure at sea level is approx millibars (1 kg/cm2)
As you move up in altitude air pressure drops

26. Why do your ears “pop” when driving up to Payson or Flagstaff?

27. You swallow to equalize the pressure on the inside of your eardrum.
As you move up in altitude the air becomes “thinner” less air molecules, thus less pressure on your eardrum
You swallow to equalize the pressure on the inside of your eardrum.

29. Why is air cooler as you increase altitude?

30. As you increase in altitude the air molecules are farther away from the reflecting heat energy of the Earth’s surface, they slow down. There are so few molecules they do not “bump” into each other, creating heat energy.

31. Layers of the Atmosphere
Earth’s atmosphere becomes colder as you climb higher. But not all layers of the atmosphere show this temp. pattern.
Layers of the Atmosphere
The atmosphere is divided into 4 layers based on temperature.

32. Troposphere Bottom layer, closest to the Earth.
Temp. decreases as altitude increases.
This layer is where weather occurs.
The rate of change in temp. in this layer is called the environmental lapse rate
The environmental lapse rate is not constant

33. Stratosphere
The temp. decreases to approx. 20 km, then there is a gradual increase temp. to about 50 km
The concentration of ozone causes this increase in temp.
Ozone absorbs ultra violet radiation from the Sun
The result is that the atmosphere becomes heated.

34. Mesosphere Thermosphere Temperature decreases as altitude increases
Temperature increases as altitude increases
This layer contains a fraction of the atmosphere’s mass
The temp change is because oxygen and nitrogen absorb short wave high energy solar radiation

35. In which layer of the atmosphere does weather occur?
Why only in this layer?

36. The Troposphere is the layer of the atmosphere where weather occurs
This is the only layer where there is an abundance of gas molecules and water vapor which affect the temp. and drives the weather