1. WEATHER SYSTEMS

2. Now lets talk about Air Masses
Quick Review
What causes wind?
Answer: uneven heating of the earth by the sun.
Is hot air high pressure or low pressure?
Answer: low pressure.
What about cold air?
Answer: high pressure
Which type of air rises? Which one sinks?
Answer: hot air (low pressure) rises, and cold air (high pressure) sinks.
Now lets talk about Air Masses

3. Air Masses
A large body of air that has nearly the same temperature and humidity throughout- They have similar properties as the part of the earth’s surface over which they form                                           

4. Why are Air Masses important?
They can cover an area of thousands of square kilometers.
They are responsible for day to day weather changes.

5. High Pressure
Low Pressure

6. Which way do the winds blow?
From ___________ pressure to _____ pressure.
high
low
Do you know what instrument we use to measure air pressure?
A Barometer

7. Cyclones
In the northern hemisphere, once wind blows into a low pressure area, it rises in a counterclockwise direction; this is called a cyclone. Low pressure areas usually have stormy weather. ** This is not the same as a tornado**

8. Anticyclones
Wind also blows AWAY from the center of high pressure. In the northern hemisphere, this wind blows in a clockwise direction. High pressure areas usually have good weather.

9. Fronts
What is a front?
It is a boundary between two air masses of different density, moisture, or temperature.
There are four types of fronts; can you name them?? _____________, ______________
_____________, and ______________
Cold front
Warm front
Occluded front
Stationary front

10. Precipitation Along a Cold Front
lifting the warm moist air ahead of it
A Closer Examination of the Animation: Initially, the cold air mass wedges into the warmer air mass ahead of it, (separated from each other by the cold front). The lighter warm air is lifted upwards by the denser cold air and if enough water vapor condenses, clouds develop.

11. Precipitation Along a Warm Front warm moist air overriding colder air
A Closer Examination of the Animation: Initially, a warm air mass (in yellow) nudges against a colder air mass (in blue) ahead of it, (separated from each other by the warm front). The lighter warm moist air behind the front is lifted upward and "overrides" the colder air.

13. Stationary Front

14. SEVERE WEATHER

15. Thunderstorms What is a thunderstorm?
- A thunderstorm is a weather event where there is heavy rain, lightning, thunder roars, and possible hail.
How do they form?
They occur in warm moist air masses and along fronts.
The air is forced upward where it is __________, and condensation occurs forming _________________clouds.
Then __________________ happens in the form of rain or hail. The rain cooled air sinks and strong updrafts of warmer air causes strong winds.
cooled
cumulonimbus
precipitation

16. Can thunderstorms cause damage?
YES!
How?
By flooding
Hail damage
Wind damage
Lightning strikes

18. What is lightning? Lightning is a bright flash of electricity produced by a thunderstorm. All thunderstorms produce lightning and are very dangerous. If you hear the sound of thunder, then you are in danger from lightning. Lightning kills and injures more people each year than hurricanes or tornadoes; between 75 to 100 people.                                              

19. What causes lightning. Lightning is an electric current
What causes lightning? Lightning is an electric current. In a thundercloud, many small bits of ice (frozen raindrops) bump into each other as they move around in the air. All the collisions create an electric charge. Once the cloud fills, with electrical charges, the positive charges form at the top of the cloud and the negative charges form at the bottom of the cloud. Since opposites attract, this causes a positive charge to build up on the ground beneath the cloud. The grounds electrical charge concentrates around anything that sticks up, such as mountains, people, or single trees. The charge coming up from these points eventually connects with a charge reaching down from the clouds and - zap - lightning strikes!              
Lightning can also form within or between clouds, not just from the cloud to the ground
Lightning also forms within and between clouds.

23. What causes thunder ?
Thunder is caused by lightning. When a lightning bolt travels from the cloud to the ground it actually opens up a little hole in the air, called a channel. The lightning heats up the air and causes it to expand. Once the lightning is gone the air collapses back due to quick cooling, and creates a sound wave that we hear as thunder. The reason we see lightning before we hear thunder is because light travels faster than sound!
Which do you think is hotter, a bolt of lightning, or the surface of the sun?
Lightning- it is 30,000 degrees Celsius. That’s 5 times hotter than the sun!!

24. Can you tell how far away a thunderstorm is?
Yes, you can use thunder to tell how far away a storm is. Next time you see a storm, count the number of seconds between when you see the lightning and hear the thunder. Take the number of seconds and divide by 5 and that will tell you how far away the storm is in miles. For example: If you counted 10 seconds between the lightning and the thunder, the lightning is 2 miles away!                                              

25. TORNADOES

26. How do tornadoes form? When thunderstorms develop, a change in wind direction and an increase in wind speed with increasing height creates an invisible, horizontal spinning effect in the lower atmosphere; this is wind shear. Rising air from the updraft of a thunderstorm tilts the rotating air from horizontal to vertical. An area of rotation, 2-6 miles wide, now extends through much of the storm. Most strong and violent tornadoes form within this area of strong rotation.
                         

27. Know the Lingo TORNADO WATCH - Tornadoes are possible in your area
      Know the Lingo        TORNADO WATCH - Tornadoes are possible in your area. Stay tuned to the radio or television news. TORNADO WARNING - A tornado is either on the ground or has been detected by Doppler radar. Seek shelter immediately! Measuring Tornadoes
The Fujita Scale
F0 gale tornado mph
Some damage to chimneys; breaks branches off trees; pushes over shallow-rooted trees; damages sign boards.
F1 moderate tornado mph
Lower limit is the beginning of hurricane-force winds. Peels surface off roofs; mobile homes pushed over; moving autos pushed off roads.
F2 significant tornado mph
Roofs torn off frame houses; mobile homes demolished; boxcars pushed over, large trees snapped or uprooted; light-object missiles generated.
F3 severe tornado mph
Severe damage. Roofs and some walls torn off well-constructed homes; trains overturned; most trees in forest uprooted; heavy cars lifted off the ground and thrown.
F4 devastating tornado mph
Well-constructed homes leveled; structures with weak foundations blown off some distance; cars thrown and large missiles generated.
F5 incredible tornado mph
Phenomenal damage. Strong frame homes disintegrate or lifted off foundations and carried considerable distance; trees debarked.

28. Where are tornadoes most likely to occur?
The geography of the central part of the United States, known as the Great Plains, is suited to bring all of the ingredients together to forms tornadoes. This includes Texas, Kansas, and Oklahoma. More than 500 tornadoes typically occur in this area every year and is why it is commonly known as "Tornado Alley".                                           

32. HURRICANES
                    

33. What is a hurricane. A hurricane is a huge storm
What is a hurricane? A hurricane is a huge storm! It can be up to 600 miles across and have strong winds spiraling inward and upward at speeds of 75 to 200 mph. Hurricanes usually lasts for over a week, moving mph over the open ocean. Hurricanes gather heat and energy through contact with warm ocean waters. Evaporation from the seawater increases their power. Hurricanes rotate in a counter-clockwise direction around an "eye." The center of the storm or "eye" is the calmest part. It has only light winds and fair weather. When they come onto land, the heavy rain, strong winds and large waves can damage buildings, trees and cars. Similar storms are called typhoons in the Pacific Ocean and cyclones in the Indian Ocean.

34. How do hurricanes form? Hurricanes form over warm ocean water of 80°F or warmer. The atmosphere must cool off very quickly the higher you go. The wind must be blowing in the same direction and at the same speed to force air upward from the ocean surface. Winds flow outward above the storm allowing the air below to rise. Hurricanes typically form between 5 to 15 degrees latitude north and south of the equator. The Coriolis effect is needed to create the spin in the hurricane.                                                                      

35. Minimal Moderate Extensive Extreme Catastrophic
      Saffir-Simpson Hurricane Scale                  
Category
Winds (MPH)
Storm Surge (Feet)
Damage 1
74-95
4'-5'
Minimal 2
96-110
6'-8'
Moderate 3
9'-12'
Extensive 4
13'-18'
Extreme 5
>155
>18'
Catastrophic

36. Can Hurricanes cause damage?
Absolutely!
Storm surges usually cause the most damage and death
Winds can destroy homes and uproot trees
Extensive rain can also cause major flooding

37. Shallow-Water Coastline
What is a storm surge?
Shallow-Water Coastline
                                                
Deep-Water Coastline

38.        Know the Lingo               TROPICAL STORM WATCH - Tropical Storm conditions with sustained winds from mph are possible in your area within the next 36 hours.
TROPICAL STORM WARNING - Tropical Storm conditions are expected in your area within the next 24 hours.
HURRICANE WATCH - Hurricane conditions with sustained winds of 74 mph or greater are possible in your area within the next 36 hours. This WATCH should trigger your family's disaster plan, and protective measures should be initiated. Especially, those actions that require extra time such as securing a boat and leaving a barrier island.
HURRICANE WARNING - Hurricane conditions are expected in your area within 24 hours. Once this WARNING has been issued, your family should be in the process of completing protective actions and deciding the safest location to be during the storm

43. How do blizzards form? A blizzard is a long-lasting snowstorm with very strong winds and intense snowfall. You need three things to have a blizzard; cold air at the surface, lots of moisture, and lift. Warm air must rise over cold air. Blizzards have winds of at least 56 km/h, temperature is below 20 degrees fahrenheit, and visibility is less than 400 meters

46. Forecasting Weather
What information do you need to know to forecast weather??
Temperature
Winds
Air pressure
Humidity
Precipitation

47. Do you know the scientific name for a weather forecaster?

48. A Meteorologist is what they’re called.
Meteorologists measure temperature, air pressure, winds, humidity, and precipitation.
They use Doppler radar, satellites, and instruments attached to balloons to get their information.
They gather information from the upper atmosphere, as well as from the earth’s surface.

49. STATION MODEL

50. Key to Features Cold Front Warm Front Stationary Front Occluded Front Trough ("TROF")          Also used to depict Outflow Boundary ("OUTFLOW BNDRY") Squall Line Dry Line Tropical Wave ("TRPCL WAVE")
A hash mark denotes a change in frontal type, as in the example below.                                    
Note: The hash mark will always be drawn perpendicular to the boundaries. They are not drawn at "triple points" (the intersection of an occluded, cold and warm or stationary front) and where a low pressure center separates the different frontal types

51. A weather map showing surface-pressure systems, air masses, fronts, and isobars (in millibars) as solid gray lines. Large arrows in color show air flow. (Green-shaded area represents precipitation.) Isotherms are similar to isobars, except they show temperature (Not Shown here)

52. QUESTIONS ???