1 / 148

Chapter Menu

Chapter Introduction Lesson 1 Describing Weather Lesson 2 Weather Patterns Lesson 3 Weather Forecasts Chapter Wrap-Up. Chapter Menu. How do scientists describe and predict weather?. Chapter Introduction. Describing Weather. What is weather?

dasha
Télécharger la présentation

Chapter Menu

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter Introduction Lesson 1 Describing Weather Lesson 2 Weather Patterns Lesson 3Weather Forecasts Chapter Wrap-Up Chapter Menu

  2. How do scientists describe and predict weather? Chapter Introduction

  3. Describing Weather • What is weather? • What variables are used to describe weather? • How is weather related to the water cycle? Lesson 1 Reading Guide - KC

  4. Describing Weather • weather • air pressure • humidity • relative humidity • dew point • precipitation • water cycle Lesson 1 Reading Guide - Vocab

  5. What is weather? • Weatheris the atmospheric conditions, along with short-term changes, of a certain place at a certain time. • Weather can change quickly or be the same for several days in a row. Lesson 1-1

  6. Weather Variables • Temperature and rainfall are just two of the variables used to describe weather. • Meteorologists use a variety of variables to predict weather, including air temperature, air pressure, wind speed and direction, humidity, cloud coverage, and precipitation. Lesson 1-2

  7. Weather Variables(cont.) • Air temperature is the measure of the average kinetic energy of molecules in the air. • Molecules in warm air move faster than molecules in cold air. Lesson 1-2

  8. Weather Variables(cont.) • Air pressureis the pressure that a column of air exerts on the air, or surface, below it. • Air pressure is measured with an instrument called a barometer. Lesson 1-2

  9. Weather Variables(cont.) • As air moves from areas of high pressure to areas of low pressure, it creates wind. • Meteorologists measure wind speed using an instrument called an anemometer. Lesson 1-2

  10. Weather Variables(cont.) • The amount of water vapor in the air is called humidity. • When the humidity is high, there is more water vapor in the air. • The amount of water vapor present in the air compared to the maximum amount of water vapor the air could contain at the temperature is called relative humidity. • Scientist use and instruments called a psychrometers or a Hygrometer to measure relative humidity and humidity Lesson 1-2

  11. Weather Variables(cont.) The dew pointis the temperature at which air is fully saturated because of decreasing temperatures while holding the amount of moisture constant. Lesson 1-2

  12. Weather Variables(cont.) • Clouds are water droplets or ice crystals suspended in the atmosphere. • A cloud that forms near Earth’s surface is called fog. • Precipitationis water, in liquid or solid form, that falls from the atmosphere. Lesson 1-2

  13. Weather Variables(cont.) Rain, snow, sleet, and hail are forms of precipitation. Lesson 1-2

  14. Characteristics of Clouds • Clouds have different characteristics because they form under different conditions and at different altitudes, which range from Earth's surface to high in the troposphere.

  15. Prefixes and Suffixes Used to Describe Clouds • Cirro = high altitude clouds means “wisp of hair” • Alto = mid-altitude clouds between 6,000 and 20,000 feet. • Nimbo prefix means “rain” suffix meaning – can produce precipitation (rain, snow or other forms of falling water)

  16. Cummulo – means heap refers to piled-up clouds • Strato – means “layer” refers to flat, wide, layered clouds

  17. Weather Variables(cont.) Rain, snow, sleet, and hail are forms of precipitation. Lesson 1-2

  18. Weather Variables(cont.) • Rain is precipitation that reaches Earth’s surface as droplets of water. • Snow is precipitation that reaches Earth’s surface as solid, frozen crystals of water. Lesson 1-2

  19. Weather Variables(cont.) The water cycleis the natural process in which water continually moves among oceans, land, and the atmosphere. Lesson 1-2

  20. Weather is the atmospheric conditions, along with short-term changes, of a certain place at a certain time. • Weather variables include air temperature, air pressure, wind, humidity, and relative humidity. Lesson 1 - VS

  21. Forms of precipitation include rain, sleet, snow, and hail. Lesson 1 - VS

  22. What is the amount of water vapor in the air called? A. air pressure B. precipitation C. dew point D. humidity Lesson 1 – LR1

  23. Which of these is measured as a percent using an instrument called a psychrometer? A. precipitation B. relative humidity C. dew point D. air pressure Lesson 1 – LR2

  24. Which term refers to the natural process in which water continually moves through the oceans, land, and atmosphere? A. dew point B. relative humidity C. air pressure D. water cycle Lesson 1 – LR3

  25. 1. Weather is the long-term average of atmospheric patterns of an area. 2. All clouds are at the same altitude within the atmosphere. Do you agree or disagree? Lesson 1 - Now

  26. Weather Patterns • What are two types of pressure systems? • What drives weather patterns? • Why is it useful to understand weather patterns? • What are some examples of severe weather? Lesson 2 Reading Guide - KC

  27. Weather Patterns • low-pressure system • high-pressure system • air mass • front • tornado • hurricane • blizzard Lesson 2 Reading Guide - Vocab

  28. Pressure Systems A high-pressure system is a large body of circulating air with high pressure at its center and lower pressure outside of the system. Lesson 2-1

  29. Pressure Systems(cont.) A low-pressure systemis a large body of circulating air with low pressure at its center and higher pressure outside of the system. Lesson 2-1

  30. Air Masses • Air massesare large bodies of air with distinct temperature and moisture characteristics. • An air mass forms when a large high pressure system lingers over an area for several days. • As a high pressure system comes in contact with Earth, the air in the system takes on the temperature and moisture characteristics of the surface below it. Lesson 2-2

  31. Air Masses(cont.) Five main air masses impact climate across North America. Lesson 2-2

  32. Air Masses(cont.) • Air masses are classified by their temperature and moisture characteristics. • Continental air masses form over land. • Maritime masses form over water. Lesson 2-2

  33. Air Masses(cont.) • Tropical air masses form in the warm equatorial regions. • Polar air masses form over cold regions. • Arctic and antarctic air masses form near the poles, over the coldest regions of the globe. Lesson 2-2

  34. Air masses are named for the two characteristics related to the regions where they formed: temperature and moisture The first word of an air mass name tells where the air mass formed and describes the moisture of the air mass. Continental = dry air mass formed over land Maritime = moist air masses that form over water The second word tells whether the air mass formed close to or far from the equator. Tropical = warm air masses formed near the equator Polar = cold air masses formed far from the equator Air Mass Characteristics

  35. Air Masses There are four types of air masses that affect weather in the United States: • Continental Polarair masses are made of cold, dry air. It moves into the United States from Canada in winter. 2. Continental tropicalair masses are made of hot, dry air. It forms over Mexico and moves north in summer. 3. Maritime Tropicalair masses form over the ocean near the equator and is made of warm, moist air. 4. Maritime Polarair masses form over the ocean waters north of the United States. It is made of cool, moist air.

  36. Fronts • A weather frontis a boundary between two air masses. • Changes in temperature, humidity, clouds, wind, and precipitation are common at fronts. Lesson 2-3

  37. Fronts(cont.) When a colder air mass moves toward a warmer air mass, a cold front forms. Lesson 2-3

  38. Types of Fronts Cold Front: The zone where cold air is replacing warmer air The heavier cold air sinks and slides under the warm air, pushing it steeply upwards. This causes cumulous and cumulonimbus clouds to form. Triangles show the direction that a cold front moves Cold fronts bring violent storms that are followed by fair, cooler weather. In U.S., cold fronts usually move from northwest to southeast. Air gets drier after a cold front moves through.

  39. Fronts(cont.) A warm front forms when lighter, warmer air moves toward colder, heavier air. Lesson 2-3

  40. Warm Front: The zone where warm air is replacing colder air The less dense warm air slides up and over the cold air. Cirrus clouds, altostratus and nimbostratus clouds develop. Semicircles show the direction that a warm front moves Warm fronts bring rain and showers. In U.S., warm fronts usually move from southwest to northeast. Air gets warmer and more humid after a warm front moves through

  41. Fronts(cont.) When the boundary between two air masses stalls, the front is called a stationary front. Lesson 2-3

  42. Stationary Front: When a cold or warm front stops moving Clouds and precipitation often form at the boundary of a stationary front. Alternating triangles and semicircles show a stationary front Stationary fronts often bring many days of continuous precipitation that can result in flooding. When the front starts moving again it returns to either being a cold or warm front.

  43. Fronts(cont.) When a fast-moving cold front catches up with a slow-moving warm front, a blocked or occludedfront forms. Lesson 2-3

  44. Occulded Fronts Fast moving cold fronts sometimes catch up to and overtake warm fronts, lifting them higher into the air. The result is an occulded front, The merging together of the cold and warm front brings a combination of cold-front weather and warm front weather.

  45. Occulded Fronts Fast moving cold fronts sometimes catch up to and overtake warm fronts, lifting them higher into the air. The result is an occulded front, The merging together of the cold and warm front brings a combination of cold-front weather and warm front weather.

  46. What type of front do each of these symbols represent? Meteorologists use lines with triangles and semicircles on them to represent fronts on a weather map. The triangles and semicircles point in the direct that the front is moving

  47. What type of front do each of these symbols represent? Stationary Warm Cold Occluded

  48. Pressure Systems Some weather maps allow us to view high and low pressure systems that control the weather. An isobar is a line connecting locations of equal barometric pressure. Isobar maps show where pressures are relatively high and low, and show us where pressure changes are gradual or dramatic over a distance.

  49. High and Low Pressure Areas High pressure causes air to sink Usually results in several days of clear sunny skies Air rises in low pressure areas and forms water droplets Usually resulting in rain and storms

More Related