Chapter 25 Vocabulary: define and give one fact: page 518

1. Chapter 25 Vocabulary: define and give one fact: page 518 • Wave cyclones • Anticyclones • Hurricane • Typhoons • Thunderstorm • Tornado • Waterspouts • Bimetal thermometer • Thermograph • Electrical thermometer • Wind vane • Radar • Station model • isobars • Air Mass • Maritime Polar • Maritime Tropical • Continental Polar • Continental Tropical • Front • Cold front • Squall line • Warm front • Stationary front • Occluded front • Polar front

2. Air Masses Form because warm air rises at the equators and cold air sinks at the poles. There are 3 convection cells in the Northern Hemisphere and 3 in the Southern Hemisphere. The Earth’s rotation and land masses cause wind to blow in different directions. In areas with small pressure differences, the air will stay long enough to develop a uniform temp and humidity. i.e. deserts, oceans, and polar areas. Section 25.1How an Air Mass Forms

3. Types of Air Masses Classified by the source region; Polar is cold and labeled “P”, Tropical are warm and labeled “T”, Masses that form over land are continental and labeled “c”, Masses that form over oceans are maritime and labeled “m”. These air masses can stay over the source region for days but will move because of wind and the Earth rotation eventually. Section 25.1How an Air Mass Forms

4. North American Air Masses Polar Air Masses Affected by seven regions, but the air can change as it moves away from it’s source region. 3 polar masses influence North America; continental polar Canadian (cP), maritime polar Pacific (mP), maritime polar Atlantic Canadian moves southeast off the Canadian ice into The United States and can moves as far south as the Gulf. Section 25.1How an Air Mass Forms

5. Polar Air Masses The Pacific air mass forms in the waters near Alaska. Very moist but not extremely cold, in winter they bring snow to the Pacific Coast and in summer fog. Most moisture lost crossing the mountains and bring dry weather to the Mid U.S. The Atlantic air mass normally moves off towards Europe, but sometimes in the winter brings cold cloudy weather to New England, in the summer cool and foggy weather. Section 25.1How an Air Mass Forms

6. Tropical Air Masses 4 influence North America; Continental Tropical, maritime tropical gulf, maritime tropical Atlantic, and maritime tropical Pacific. cT comes from the Deserts of Northern Mexico and bring clear, dry and very hot weather. mT Atlantic and Gulf bring mild cloudy weather in winter and hot humid weather, thunderstorms and hurricanes in the summer. mT pacific rarely reach the coast, but in the winter can bring heavy rain and thunderstorms. Section 25.1How an Air Mass Forms

7. Front Cold front Squall line Warm front Stationary front Occluded front Polar front Wave cyclones Anticyclones Hurricane Typhoons Thunderstorm Tornado Waterspouts Chapter 25 section 2 Vocabulary: define and write sentences

8. Essential Question • Compare the characteristic weather patterns of cold fronts and those of warm fronts • Describe how a wave cyclone forms • Describe the stages in the development of hurricanes, thunderstorms and tornados

9. Fronts Types of Fronts A boundary between air masses Cold Front – Cold air overtakes warm air and lifts the warm air – a squall line forms on this front Warm Front – Warm air overtakes cold and rises in a gradual slope Stationary Front – is when the air masses are not displaced Occluded Front – is when a cold front push the warm air completely off the ground Section 25.2Compare the characteristic weather patterns of cold fronts and those of warm fronts

10. Polar Fronts Wave Cyclones A Polar front circles the earth at 40 to 60 degrees latitude in both hemispheres. In winter it is in the Middle of North America . In Summer it is North of the Great lakes The boundary along a polar front is where wave cycles form. They can grow to 2,500 km in diameter, with winds that blow in an upward circle path around the low pressure center. They have major influences on our weather. Section 25.2Compare the characteristic weather patterns of cold fronts and those of warm fronts

11. Stages of a Wave Cyclones Anticyclones Stage one there is a stationary front, the winds move parallel to the front in opposite directions. Stage two an intensifying low pressure region develops along the front, bringing stormy weather. Stage three last about 24 hours and continues to move east in North America. The process can restart. The anticyclone spins clockwise and brings dry warm air to a region or fair weather. The air is sinking Section 25.2Describe how a wave cyclone forms

12. Hurricanes Has winds over 120 km/hr No more then 700 km in diameter A storm starts with warm moist air evaporating from the ocean rapidly The release of latent heat increases the rise of air Winds increase towards the eye The eye is clear and calm The danger is due to raising sea levels and large waves. Section 25.2Describe the stages in the development of hurricanes, thunderstorms and tornadoes

13. Thunderstorms Lightning, thunder and strong winds accompany this type of storm. High surface temperatures cause the rapid rise of warm moist air. In stage one a Cumulus clouds form or Cumulonimbus. Stage two is called the mature stage and is when the storm becomes dark cumulonimbus cloud with heavy torrential rains The final stage or dissipating is when the storm has used the available water vapor and the winds end. Section 25.2Describe the stages in the development of hurricanes, thunderstorms and tornadoes

14. Tornadoes Are the smallest, most violent and shortest lived severe storms. Starts when a thunderstorm meets high altitude horizontal winds. This may form a narrow, funnel shaped, rapidly spinning extension that may move downward to the ground. Not more than 100 m wide, path is destroyed. Winds can reach 400 km/hr Most common in an area called tornado alley in the United States. When they form over water they are called waterspouts and usually weaker. Section 25.2Describe the stages in the development of hurricanes, thunderstorms and tornadoes

15. Describe the types of instruments used to measure the weather Chapter 25 section 3: Essential Question

16. Weather Instruments Measuring Air Temperature Barometers, psychrometers, rain gauges, thermometer, anemometer, radiosonde and radar Celsius and Fahrenheit used in the United States. 3 types of thermometers Liquid use Mercury or Alchol to determine the temperature Bimetal that expand or contract to temperature, a thermograph measures the temperature change Electrical use the flow of electric current through certain materials Section 25.3

17. Measuring Wind Speed and Direction Measuring upper-atmospheric conditions An anemometer measures in m/sec, MPH, or knots. A wind vane tells you the direction the wind comes from. The points into the wind. A radiosonde is attached to a helium filled balloon to measure weather conditions in the upper atmosphere Radar can also be used to detect water droplets, Doppler can even give direction Satellites can also be used to measure cloud. Land and sea temperatures. Section 25.3

18. Chapter 25 section 4 Essential question Explain how a weather map is made

19. Forecasting the weather History – more then 4,000 years of trying to predict the weather The invention of the thermometer and barometer made forecasting possible In 1844 the telegraph made it so data could be shared quickly 1870 the U.S. formed the Weather forecasting agency, renamed the National Weather Service Data is collected from around the world every 6 hours Section 25.4

20. Making a Weather Map Section 25.4Cornell Notes

21. Section 25.4

22. Types of forecasting Controlling the weather Two types daily and long term Daily – weather for the next 24 hours – local daily can be as much as 5 days Long range forecast covers monthly & seasonal outlooks Cloud seeding has been used to reduce the intensity of storms with limited results. Some experimentation still continues. Section 25.4