Chapter 13 Weather

1. Chapter 13 Weather S6E4-Understand how the distribution of land and oceans affects climate and weather. E.Q.: How do scientist describe and predict weather?

2. Lesson 1: Describing Weather • What is weather? • http://pmm.nasa.gov/education/videos/nasa-our-world-what-weather • Weather is the atmospheric condition, along with short-term changes, of a certain place at a certain time. • In other words our weather outside is not the same as the weather in Florida right now.

3. Lesson 1: Describing Weather Weather Variables air temperature air pressure wind speed and direction Humidity cloud coverage precipitation. • Meteorologist use several variables to predict the weather.

4. Lesson 1: Describing Weather • Air Temperature • The measure of kinetic energy or movement of molecules in the air. • Air temperatures vary with time of day, season, location, and altitude.

5. Lesson 1: Describing Weather • Air Pressure • http://www.watchknowlearn.org/Video.aspx?VideoID=8286&CategoryID=7316 • The force a column of air applies on the air or a surface below. • Air pressure decreases as altitude increases. • Also referred to as barometric pressure.

6. Lesson 1: Describing Weather • Wind • As air moves from areas of high pressure to areas of low pressure, it creates wind. • Wind is named by the direction it blows from. Westerlies flow from west to east. • An anemometer measures wind speed.

7. Lesson 1: Describing Weather • Humidity • The amount of water vapor in the air. • When the humidity is high there is more water vapor in the air. • High humidity might make your skin feel sticky or sweat might not evaporate as quickly.

8. Lesson 1: Describing Weather • Relative Humidity • The amount of water vapor in the air compared to the maximum amount of water vapor the air could hold at a certain temperature. • Like a sponge, air can only hold so much water vapor. • Temperature determines the amount of water vapor air can hold.

9. Lesson 1: Describing Weather • Dew Point • The temperature at which air is staturated and condensation can occur. • If the temperature is above 0º C, dew forms. • If the temperature is below 0º C, frost forms.

10. Lesson 1: Describing Weather • Clouds and fog • Clouds are water droplets or ice crystal suspended in the atmosphere. • A cloud that forms near Earth’s surface is fog.

11. Lesson 1: Describing Weather Precipitation Type of Precipitation Rain Snow Sleet Hail • Water in liquid or solid form, that falls from the atmosphere.

12. Lesson 1: Describing Weather • The Water Cycle is the series of natural processes by which water continually moves among oceans, land, and the atmosphere.

13. Lesson 1: Describing Weather Show what you know! • What is weather? • What variables are used to describe weather? • How is weather related to the water cycle?

14. What is a high pressure system? Lesson 2: Weather Patterns • A whirling mass of cool, dry air that generally brings fair weather and light winds. • When viewed from above, winds spiral out of a high-pressure center in a clockwise rotation in the Northern Hemisphere. These bring sunny skies. • A high pressure system is represented as a big, blue H.

15. Lesson 2: Weather Patterns What is a low pressure system? • A whirling mass of warm, moist air that generally brings stormy weather with strong winds. • When viewed from above, winds spiral into a low-pressure center in a counterclockwise rotation in the Northern Hemisphere. • A low pressure system is represented as a big, red L.

16. Lesson 2: Weather Patterns

17. Lesson 2 Weather Patterns • What is an air mass? An air mass is an extremely large body of air whose properties of temperature and moisture content (humidity), at any given altitude, are fairly similar in any horizontal direction.

18. Lesson 2 Weather Patterns • Air masses cover large (hundreds of miles) areas. • Air masses control the weather for a relatively long time period: from a period of days, to months. • Most weather occurs along the periphery of these air masses at boundaries called fronts.

19. Lesson 2 Weather Patterns • There are 4 general air mass classifications categorized according to the source region: • Polar • Tropical • continental • marine 

20. Lesson 2 Weather Patterns • There are 4 general air mass classifications 1.) Polar latitudes (P) - located poleward of 60 degrees north and south  2.) Tropical latitudes (T) - located within about 25 degrees of the equator  3.) Continental (c) - located over large land masses, dry  4.) Marine (m) - located over the oceans

21. Lesson 2: Weather Patterns

22. Lesson 2 Weather Patterns

23. Lesson 2 Weather Patterns What is a front? • A front is a boundary between two different air masses, resulting in stormy weather. • A front usually is a line of separation between warm and cold air masses. 

24. Lesson 2 Weather Patterns • Cold front-colder air mass moves toward a warmer air mass.

25. Lesson 2 Weather Patterns • Warm fronts-warmer air moves towards cooler air.

26. Lesson 2 Weather Patterns • Stationary front-stalls for several days with warm air on one side and cold on the other side of it.

27. Lesson 2 Weather Patterns • Occluded fronts-when a fast moving cold front catches up to a slow moving warm front. Usually brings precipitation.

28. Lesson 2 Weather Patterns • Some weather events can cause damage, injuries, and even deaths. • These events are referred to as severe weather.

29. Thunderstorms • https://www.youtube.com/watch?v=IatoWCinM9w Also known as electrical storms because of their lightening. 3 Stages of a thunderstorm

30. Tornadoes • http://video.nationalgeographic.com/video/101-videos/global-warming-101?source=relatedvideo • https://www.youtube.com/watch?v=gieSbj2svwY A violent whirling, whirling column of air in contact with the ground.

31. Hurricanes http://www.pbslearningmedia.org/resource/ess05.sci.ess.watcyc.hurrlife/how-hurricanes-form/ https://www.youtube.com/watch?v=a-SnxC-BkPo http://www.accuweather.com/en/weather-video/video-inside-a-hurricanes-eye/1116007390001 An intense tropical storm with winds exceeding 119 km/h or around 74 mph.

32. Winter Storms Winter weather can also be severe. Snow and ice can make driving dangerous. A blizzard is a violent winter storm with freezing temperatures, strong winds, and blowing snow.

33. Lesson 2 Weather Patterns • The U.S. Weather Service issues watches and warnings during severe weather. • It is important to know how to protect yourself during dangerous weather. • During thunderstorms, stay inside and away from metal objects and electrical cords. • If outside, stay away from water, high places, and isolated trees.

34. Lesson 2: Weather Patterns Show What You Know! • What are two types of pressure systems? • What drives weather patterns? • Why is it useful to understand weather patterns?

35. Lesson 3: Weather Forecast Measuring the weather • Meteorologist use specialized instruments to measure conditions in the atmosphere. • Thermometer-Temperature • Barometer-Air Pressure • Psychrometer-Relative Humidity • Anemometer-Wind speed

36. Lesson 3: Weather Forecast • Surface report • Describes a set of weather measurements made on Earth’s surface. • Weather variables are measured by a weather station, (a collection of instruments that measure temp, air pressure, humidity, wind, precipitation, and cloud amounts.

37. Lesson 3: Weather Forecast • Upper-air report • Describes wind, temperature, and humidity conditions above Earth’s surface. • Measured by radiosonde, (weather instruments carried many km above ground by a weather balloon) • Reports are made twice a day at hundreds of locations around the world.

38. Lesson 3: Weather Forecast Satellites • Meteorologist use visible light and infrared satellite images to identify fronts and air masses.

39. Lesson 3: Weather Forecast Doppler Radar • A specialized type of radar that can detect precipitation as well as the movement of small particles, which can be used to approximate wind speed.

40. Lesson 3: Weather Forecast Weather Maps • Station Model-displays data from different measurements for a particular location. • Isobars are lines that connect all places on a map where pressure has the same value.

41. Lesson 3: Weather Forecast Predicting the Weather • Meteorologists analyze data from various sources, such as radar and computer models to prepare forecasts. • Computer models are detailed computer programs that solve a set of complex math formulas.

42. Lesson 3: Weather Forecast Show what you know! • What instruments are used to measure weather variables? • How are computer models used to predict the weather?