1. Weather & Climate

2. Weather Intro How much do you already know about weather?
What cycle is the basis of our weather?
What causes precipitation to occur?
Where do storms usually occur?

3. Weather
Temporary behavior of atmosphere (what’s going on at any certain time)
Small geographic area
Can change rapidly
The study of weather is called meteorology
Someone who studies weather is called a meteorologist

4. Climate Long-term behavior of atmosphere (100+ years)
Large geographic area
Very slow to change

5. SEASONS

6. POLAR 90o -60o latitude Cool summers, cold year-round Dry
EX: Arctic and Antarctic

7. TEMPERATE 60o-30o latitude True Seasons Variety of climate patterns
Moderate precipitation
(rain/snow)
EX: United States

8. TROPICAL 30o - equator No winter, warm year-round
High temp, rainfall, humidity
EX: Caribbean

10. What Factors Affect Weather & Climate?
The Sun
The Water Cycle
The Atmosphere
The Ocean

11. How Does the Sun Affect Weather?
It warms the atmosphere & oceans
It creates climate zones
It keeps the water cycle going
It affects weather patterns

12. The Water Cycle
All the water on the planet is recycled in this manner!

13. Parts of the Cycle
Evaporation—Water going from a liquid to a gas (gains energy from the sun)

14. Parts of the Cycle
Condensation—Water going from a gas to a liquid (cools or loses energy)
When this happens in the atmosphere, CLOUDS form.

15. Parts of the Cycle
Precipitation—when water falls out the atmosphere. Forms when the water droplets in clouds become too heavy to stay up.
Liquid water = rain
Frozen water = snow, sleet, or hail

16. Parts of the Cycle
Transpiration—evaporation of water from/out of plants. Locate this on the diagram!

17. The Water Cycle

19. Atmosphere
The atmosphere is a mixture of gases that surrounds the Earth
Nitrogen (78%), Oxygen (20.9%),
Less than 1% Ar, CO2, He, Methane, Krypton, Hydrogen
Has five different layers; each has different properties
Air Temperature and Pressure change with altitude
Weather occurs in the layer closest to Earth (troposphere)

21. Atmosphere

22. Atmosphere

23. Exosphere - the outermost layer of the Earth's atmosphere, where atmospheric pressure and temperature are low.
Ionosphere - the atmospheric layer between the mesosphere and the exosphere; it is part of the thermosphere.
Mesosphere - the atmospheric layer between the stratosphere and the ionosphere.
Stratosphere - the atmospheric layer between the troposphere and the mesosphere. The stratosphere is characterized by a slight temperature increase with altitude and by the absence of clouds.
Thermosphere - the layer of the atmosphere located above part of the ionosphere (starting at the coldest part of the atmosphere) and below outer space; it consists of the exosphere and part of the ionosphere.
Troposphere - the lowest layer of the Earth's atmosphere. The weather and clouds occur in the troposphere.

24. Air Masses An air mass is a body of air with a certain temperature and
moisture level
Can be warm or
Cold
Can contain a lot of
moisture or not a lot of
moisture

25. Fronts where air masses meet 4 Types: Warm Cold Occluded Stationary
Fronts are places
where air masses
meet
4 Types:
Warm
Cold
Occluded
Stationary
Each kind can bring different kinds of weather

28. Air Pressure How much the earth’s atmosphere is pressing down on us
Measured with a barometer
If it changes, then new weather is on the way:
Falling Air Pressure = stormy weather coming
Rising Air Pressure = fair weather coming
Steady Air Pressure = no change is coming

29. Demo-The hot plate is turned on with a spiral above it
What happens to the air above the hot plate?
Why does the spiral start to spin?
What direction is it going? (clockwise or counterclockwise?)
When the spiral is moved to colder air, how does the motion change?
WHY…What is going on with the air?

30. Air Currents
Determined by heat and temperature of the earth’s surface, and the air around it.
Conduction: Heat transfer is from direct contact between heat source and matter
Ex-When heat from blacktop or sand is transferred directly to a bare foot
Convection: Heat transfer is from indirect contact
Ex-When the surface of the earth heats up, the air just above the surface rises. It rises, it also cools and therefore, it sinks back down. This rising and sinking creates surface winds (convection currents)
Radiation: Travels in waves
Ex-The sun’s energy traveling to Earth

31. Winds Winds are created from differences in air pressure
Moves from areas of HIGH to LOW pressure
Greater the difference in pressure, the FASTER the wind blows
Measured with wind vanes (or wind sock) and anemometers or you can estimate with the Beaufort Wind Scale

32. Beaufort Wind Scale

33. Local Winds
Day time breeze towards land because warm air over land rises (LOW), then cools and sinks (HIGH) towards water. Wind blows from High to Low.
Night time breeze towards water because warm air over water rises (LOW), then cools and sinks (HIGH) towards land. Wind blows from High to Low.

34. Global Winds
Thousands of kilometers long; can cause weather to move in different directions
Jet stream, prevailing westerlies, doldrums, horse latitudes, trade winds
Caused by the temperature difference in different regions
Hot Tropical Regions—causes air to rise
Cold polar Regions—causes air to sink

35. Global Winds Also affected by Earth’s Spin
Coriolis Effect = causes winds to curve to the right
in the N. Hemisphere; to the left in the S. Hemisphere

36. Relative Humidity
Measure of the amount of moisture in the air compared to what the air could hold
How “full” of water the air is
Expressed as %
100% relative humidity = saturated air
(precipitation is occurring)

37. Relative Humidity
1. Warm air holds more moisture than cool air (more space for water vapor between air molecules)
2. As air warms, relative humidity
increases
3. As air cools, relative humidity
decreases

38. Dew Point
Dew point is the temperature at which the air is saturated (100% relative humidity)
Several events can occur when the dew point temp. is reached:
1. If dew point temp. is above freezing:
a. water vapor condenses as liquid
b. dew will form on surfaces
c. cloud droplets will form in air
2. If dew point temp. is below freezing:
a. water vapor condenses as a solid
b. frost on surfaces
c. snow (or hail) in the air

40. Severe Weather

41. Thunderstorms Requires a mature cumulonimbus cloud Signs
Sudden reversal of wind direction
Noticeable increase in wind speed
Sudden drop in temperature

42. Thunderstorms Possible weather a. heavy rains (flash floods)
b. lightning (forest fires)
c. thunder (frightens animals)
d. hail (crop damage)
e. tornadoes
f. strong, gusty winds
Safety Rules
a. Stay indoors
b. Prepare for lightning, strong winds
c. Listen to radio/TV for tornado
watch/warning
d. Thunderstorms don’t last long

43. Lightning Storms
Cumulonimbus cloud becomes electrically charged and ground below has opposite charge
Lightning strike: flow of current thru air (a poor conductor) from the – to the +
Lightning can flow from cloud to ground, cloud to cloud, and from ground to cloud
Bright light is caused by glowing air molecules heated by the current
Lightning follows the path of least resistance (easiest way to positive)
Lightning rod offers lightning an easy, safe path to the ground (+)

44. Lightning Storms Sound travels @ about 1100 ft/sec in air
Thunder is the shock wave caused by the explosive expansion of heated air
Sound about 1100 ft/sec in air
5,280 ft in one mile
Distance from you to lightning = number of seconds between seeing the flash and hearing the thunder divided by 5.
(5,280 ft / 1100 ft/sec = 5 seconds)

45. Types of Lightning
Streak or bolt
Single or branched lines of light

46. Types of Lightning Sheet a. shapeless flash over wide area
b. a cloud-to-cloud bolt hidden by the clouds

47. Types of Lightning
Other Types a. heat, ribbon, beaded (types of bolt) b. ball (only other shape lightning can have)

48. Safety rules for lightning storms
Stay indoors
Stay away from anything that conducts electricity (stove, sink, telephone, TV)
Get out of the water and off of small boats
Stay away from open doors, windows, fireplaces
Stay in your car (very safe place to be)
Don’t stand under lone trees or in open places
Avoid hilltops
If your hair stands on end, or your skin tingles, drop to the ground but try to keep as little contact with the ground as possible
People struck by lightning

49. Tornado (a.k.a twister, cyclone)
Counterclockwise column of rotating air extending from cumulonimbus cloud
Per square foot, is the most destructive atmospheric event
Rated by wind speed (EF1 to EF5)
“Tornado season” = April, May, June
Tornadoes that form over water are called “waterspouts”
How do tornadoes form

51. Tornado Behavior of a tornado is unpredictable Typical tornado will:
1. Occur between 3-7 pm
2. Travel 4 miles
3. Be m wide
4. Travel mi/hour
5. Have wind speeds up to 300 mi/hr
6. Produce extremely low pressure
7. Be dark due to debris picked up

52. Tornado 1. Take immediate action!
2. Move away from tornado’s path (90O to the
path of the twister)
3. Lie flat in nearest ditch, etc.
At home
a. open windows, doors
b. seek shelter in basement or under heavy table in middle of house

53. Tropical Cyclone Nicknames 1. Atlantic: hurricane
2. SE Asia, Japan: typhoon
3. Australia: willy-willy
4. Indian Ocean: cyclone
Rated by wind speed (category 1 to 5)
Starts and grows over warm ocean water
Composed of bands of thunderstorms spiraling counterclockwise around a low pressure center

54. Tropical Cyclone Characteristics Several hundred miles wide
Last many days (even weeks)
Winds from mi/hr
Contains an “eye”
Small region of low pressure
Surrounded by highest winds
Calm, peaceful, sunny weather
Last for about 1 hour as hurricane passes by

55. Tropical Cyclone Safety 1. Prepare for high winds
2. Prepare for flooding (greatest source of damage)
Up to 20 in. of rain
Flooding by coastal water
3. Prepare for thunderstorms
4. Have on hand stored food, water, blankets, candles, matches, radio, etc.
5. Seek shelter