1. The study of Earth’s atmosphere
Meteorology
The study of Earth’s atmosphere

2. Weather vs. Climate
Weather: Wind, temperature, precipitation, cloud cover and air pressure. Can be localized.
Climate:long-term wx conditions over a large area. Classification based upon temp. and precip.

3. Atmosphere Composition: 78 % Nitrogen 21 % Oxygen
.036% Carbon Dioxide*
Rest: water vapor; dust; ozone; argon
* Has the most impact, meteorologically speaking

4. Refer to Atmosphere Layers Hand Out
(A)Troposphere: up to ~12km. Where we live, where wx occurs.
Temp.↓as altitude↑.
Rate of change:
6.5 oC/km.
Thinnest layer
(B)Stratosphere:
~12km-50km
Contains the O3 (Ozone) Layer

5. UV rays + O3 O2 + O O3 Stratosphere cont’d
As elevation increases, temperature increases due to the absorption of radiation by the O3 Layer
UV rays + O3 O2 + O O3

6. Ozone Layer and Stratosphere cont’d
This rxn in the O3 Layer causes UV rays to get absorbed. If the rxn is disrupted (as in below), then holes in the O3 layer form. This allows more UV rays to reach the earth’s surface, increasing skin cancers, etc.
UV rays + O3 O + O2 + CFC’s
CFCO + O2
The result:
Depleting the Ozone Layer so there is less Ozone to react w/the UV rays, more UV rays get to Earth’s surface

7. Layers and layers continued
C.)Mesosphere: extends to 80 km. As altitude Temp.
Upper part called mesopause. Avg temp. -90oC

8. Just one more layer……….
D.)Thermosphere: ( km) contains the ionosphere in its lower portion.
Temp. increases as altitude increases due to the absorption of short-wave, high-energy solar radiation

9. Not quite done yet…………. Auroras occur in the ionosphere.
Energetic electrically charged particles (mostly electrons) accelerate along the
magnetic field that surrounds the Earth.
They collide with gas atoms and solar radiation, causing the
atoms to give off light.

10. Heat Transfer
Conduction: transfer of heat through matter by molecular activity. Energy is transferred through collisions of one molecule to another

11. Heat Transfer
Convection: the movement of matter due to the differences in density which is caused by differences in temp.

12. Heat Transfer
Radiation:transfer of heat energy through space via electromagnetic waves. Electromagnetic waves can travel in the absence of matter (mechanical waves, like sound, can not).

13. Meet ROYGBIV (Not who….what)
ROYGBIV stands for the electromagnetic spectrum (light)
R=Red
O=Orange
Y=Yellow
G=Green
B=Blue
I= Indigo
V=Violet
When “white” light (from the sun) is separated (like a rainbow), it separates into these colors

14. Wavelength
long
short V I S B L E
Red Orange Yellow Green Blue Indigo Violet
infrared
Ultra-Violet
Low Frequency – Energy High

15. Weather Principles and Vocab……

16. ! Pressure= Force/area Pressure is measured in Pascals (Pa)
1 Pa = 1 Newton (force)/m2 (area)
AIR PRESSURE is measured in milli bars (mb)
1 mb = 100 Pa
Standard air pressure at sea level = mb (aka 29.9 inches of mercury)

17. What is needed for precipitation?
Temp. of pocket of air >Temp. of environment (Tp>Te) This causes:
Vertical transport, which causes Instability.. Need pocket of air to rise in order for it to cool, condense and precipitate
Condensation/Moisture. USUALLY 75% relative humidity

18. THEREFORE…..
IN GENERAL, precipitation will not occur when a high pressure system is in control.
If the pressure is high, then the air SUBSIDES (sinks)….if it sinks will not get the instability, etc needed for precipitation.

19. So what do you get w/a high pressure system?
USUALLY…fair weather, light winds
Tp<Te=subsidence/stable condition

20. What gives “bad” weather/precipitation?
IN GENERAL, a LOW PRESSURE system
Tp>Te, causing the air to rise, get the instability, condensation, etc

21. Low Pressure System
Pressure is low so the surrounding air pressure, in contrast, is high.
High pressure wants to go to low
That replacing air rises….causes the instability and condensation needed for precip/poor wx

22. What causes Pressure Differences?
Temp. differences Density differences
Pressure differences

23. So……WHAT causes the temp differences???????
Uneven heating/ cooling of the Earth’s surface.
These cause AIR MASSES that then cause FRONTS/FRONTAL SYSTEMS

24. Air Masses Continental Polar cP) Maritime Polar(mP) mP cP
Continental Tropical (cT)
Page 603 in book
Maritime Tropical (mT) mT
Air Masses

25. Air Masses Names and Properties
Maritime Polar (mP)
Continental Polar (cP)
Continental Tropical(cT)
Maritime Tropical (mT)
Moist (from off the ocean), cold from the “poles”
Dry from off the continent(land), cold from the “poles”
Dry from off the land; warm from equator
Moist from off the ocean, warm from the equator

26. FRONTS
Warm front
Cold front
WARM AIR
COLD AIR

27. Warm Front
Incoming air is warmer (less dense)than air it is “replacing”
Warm “over runs” air it is replacing
Often get cirrus clouds as warm front approaches
Can get precip. Usually not “violent”(ex: showers, drizzle)

28. Cold Front
Incoming air is colder (more dense) than the air it is replacing
“Replaced” air rises quickly
Get precip that could be violent (thunderstorms, tornadoes)

29. Stationary Front
Unsettled wx stalls. Usually “drizzley”
Overcast

30. Occluded Front Cold front catches up to warm front
Weather can be VERY violent (more than a cold front) thunderstorms, tornadoes

31. Definitions:
Dewpoint:The temperature at which air becomes totally saturated w/water
Humidity: amount of water vapor in the air
Relative Humidity: air’s water vapor content to its water vapor capacity. Capacity can change w/temp. HOW/WHY?
(temp. capacity )

32. Formula for RH Yeah!!! Math in Science
Relative Humidity (RH)=
Absolute humidity/Capacity X 100=%
Ex: at 10oC capacity is 11.0g/cm3
The actual humidity(absolute)might be 5.5g/cm3, so……
5.5/11 x 100=50% RH