1. Weather and Severe Storms

2. The Sun provides the energy that drives Earth’s weather by unevenly heating the land and water, and by heating the equator and poles by different amounts.
The Sun as the driving force behind for wind and water currents and earth’s temperatures

3. Air masses, of different temperature and humidity, move from areas of high pressure to areas of low pressure, creating wind.

4. Why would the area indicated in the map below be considered unseasonably warm?
Look at the jet stream.
Since the jet steam is so far north, the warm tropical air from the South would come further north

5. Climate is the long term pattern of temperature and precipitation in an area

6. Weather is the short term variations in temperature, humidity, air pressure, and wind.

7. Weather happens every day, but only some days have storms

8. Storms vary depending on their temperature, if they are coming off the ocean or continent, and the season.

9. The severity of the storm depends on whether or not they strike a populated area.

10. Examples of severe storms
Thunder and lightning storms
Tornadoes
Hurricanes
Blizzards
For the test you need to be able to:
distinguish one storm from another
and
identify why they only form in certain areas of world during certain times of the year

11. Thunderstorms What is it?
A storm with thunder and lightning and typically also heavy rain or hail.

12. What causes a thunderstorm?
Moisture, unstable air, and lift.
You need moisture to form clouds and rain. You need unstable air that is relatively warm and can rise rapidly. Finally, you need lift. This can form from fronts, sea breezes or mountains.

13. When are thunderstorms most likely to occur
When are thunderstorms most likely to occur? Thunderstorms can occur year-round and at all hours. But they are most likely to happen in the spring and summer months and during the afternoon and evening hours. Why?

14. Warm, moist air rises, forming cumulus, then cumulonimbus clouds.
The water vapor condenses, it collects together and forms rain drops or hail.
As rain or hail falls, a downdraft is created, which cuts off rising warm air and stops the storm.

15. Thunderstorm Formation

16. Lightning
Uneven electrical charges occur in a cloud as rain drops and hail move in a convection current in the cloud.
The lightning occurs in an attempt to equalize the uneven charges.

17. Tornadoes

18. Tornadoes
What is a tornado? A tornado is a violent rotating column of air extending from a thunderstorm to the ground.

19. Other Names for Tornadoes
Tornado comes from the Spanish word, tronada, which means “thunderstorm.” Other names for tornadoes are twisters, dust devils, whirlwinds, waterspouts, and cyclones.
R- Dust Devil, Center- Water Spouts, L- Fire Devil

21. In severe thunderstorms, winds are moving in different directions and at different speeds at different heights.
This difference in wind direction and wind speed is called wind shear.

22. Wave Clouds (or Tsunami Clouds, or Kelvin-Helmholtz Clouds) seen in Van Gogh’s “Starry Night” painting

23. A strong updraft tilts the wind shear and produces rotation inside the tornado. A funnel cloud appears.

24. Tornado Alley
Tornadoes in the U.S. are most likely to occur in a region known as Tornado Alley.

25. Did Dorothy from the Wizard of Oz live in “Tornado Alley?”

26. Any place thunderstorms occur, a tornado can happen
Any place thunderstorms occur, a tornado can happen. In the United Kingdom, Polar continental air mixes with Tropical Maritime air producing tornadoes

27. Tornado Categories
The Fujita-Pearson Tornado Intensity Scale or F-scale ranks tornadoes by their wind speed.
F0- winds mph
F1- winds mph
F2- winds mph
F3 – winds mph
F4 – winds mph
F5 – winds > 261 mph

28. Tornado Precautions Go to a basement, if you have one.
Get in the innermost room of your house. Avoid rooms with windows. Bathrooms are good.
Crouch with arms above your head.
If outside, lie in a ditch or get under a bridge.
If you live in an area with a frequency of tornadoes, listen to forecasts.

29. Hurricanes

30. Hurricanes
What is a hurricane? Hurricanes are a system of strong winds spiraling inward and upward at speeds of 75 to 200 mph counterclockwise around a low pressure center
Swirling air rises and cools, forming clouds and precipitation
Hurricanes form over warm (82 degree +) water and have winds 74+ mph

31. Formation of a Hurricane
Hurricanes are storms that form over tropical waters. The hurricanes that affect the eastern coast of the United States form off the western coast of Africa where the water is warm, the air is humid, and the winds converge.

32. Tropical Disturbance
Hurricanes start out as a group of storms that begin to rotate when they meet converging winds. These storms create violent seas that send more moisture into the air. The water vapor rises and helps the wind increase in speed. If the storm holds itself together for 24 hours, we call it a tropical disturbance.

33. Tropical Depression
Tropical cyclones are areas of low pressure that develop over tropical waters. We call them tropical depressions if their wind speeds are more than 25 mph and less than 38 mph.
A tropical disturbance becomes a tropical depression if it lasts more than 24 hours.

34. Tropical Storm
A tropical depression becomes a tropical storm when its winds rise above 38mph.
It is called a tropical storm if the winds are between 39 and 73 mph.

35. Hurricanes
A tropical storm becomes a hurricane when its winds exceed 73 mph.

36. Hurricane Categories Category 1 – Winds between 74- 95 mph
Category 5 – Winds above 156 mph

38. Hurricane Facts
Hurricanes can be very big, even as big as the state of Ohio! They can be seen from outer space.
The entire formation and life of a hurricane takes days or weeks.
Because hurricanes seldom travel in straight paths, meteorologists predict several paths.
Hurricanes usually lose power as they travel over land.
Hurricanes destroy beaches, buildings, and vegetation.
Hurricanes bring strong winds, heavy rain, storm surges, flooding, and tornadoes.

39. Hurricane Protection Watch weather forecasts.
Board up all windows and doors
Have bottled water, food, batteries, medicine, and important documents
Call someone and let them know where you are
Photograph valuables for insurance
Take care of your pets

40. Hurricane Isabel

41. Hurricane Andrew
The path of Hurricane Andrew over three consecutive days can be seen below.

43. Super Storm Sandy

44. Blizzards
A blizzard is a long-lasting snowstorm with very strong winds (35+ mph) and intense snowfall.

45. When and where do blizzards occur?
They are common in winter when the jet stream travels south and a cold northern air mass comes in contact with a warmer, semi-tropical air mass.

46. When the cold, continental polar air mass travels over a lake, it can pick up more moisture and produce “Lake Effect” snow blizzards

47. Lake Effect Snow

48. Blizzards & Ice Storms

49. Review Which is larger, a hurricane or a tornado?
Which moves faster, a hurricane or a tornado?
Which lasts longer?
Where do hurricanes form?
Where do tornadoes form?
What do we call the area of the US that has a high occurrence of tornadoes?
How long do tornadoes last?
How long do hurricanes last?
Name two precautions in the event of a tornado.
Name two precautions in the event of a hurricane.

50. Severe Weather Typical Time of Year Type of Storm Where Forms
Safety Rules
Within large cumulonimbus clouds
Seek shelter, avoid trees and water.
Spring or Summer
Thunderstorms
Move to a storm shelter or basement if possible; stay away from windows and doors.
Cumulonimbus cloud
Spring, early summer
Tornado
Late summer and into autumn
Evacuate or move inside a well-built building.
Over warm ocean water
Hurricane

51. WEATHER SERVICE MAPS
ISOTHERMS are lines joining places on the map that have the same TEMPERATURE
Do you see the connection between “isotherm” and “thermometer”

52. WEATHER SERVICE MAPS
ISOBARS are lines joining places on the map that have the same AIR PRESSURE
Iso means “equal”
Bar means “pressure”
Why doyou think it’s called a barometer?