Meteorology Notes
Chapters: 20-1, 21, 22-1, 22-2
Standard: 8.E.1.3 Students are able to explain the factors that create weather and the instruments and technologies that assess it.
Ch. 20 Objectives
- Explain how heat energy affects the changing phases of water
- Explain what absolute and relative humidity are, and describe how they are measured
- Describe what happens when the temperature of air decreases to the dew point or below
20-1 Atmospheric Pressure page 543
I. Changing Forms of Water
A. Water in our atmosphere exists in 3 states: solid (ice), liquid (water) and gas (water vapor)
1. Water changes from one phase to another when __________________is absorbed or released
2. The heat energy that is absorbed or released by a substance during a phase change is called latent heat. (pg. 543)
3. ___________________________: how most water enters the atmosphere
a.) Because the largest amounts of solar energy reach Earth near the equator, most evaporation takes place over the oceans of the ________________________.
b.) Water vapor can also enter the atmosphere through:
Evaporation from lakes, ponds, steams, soil, and transpiration –plants release water into the atmosphere
4. ________________________: the process in which a solid changes directly into a gas
a.) Scenario: when the air is dry and the temperature is below freezing, ice and snow may sublimate into water vapor
II. Humidity
A. Water vapor in the atmosphere is known as humidity; it’s controlled by rates of ____________________ and evaporation
1. The higher the temperature is, the higher the rate of evaporation is
2. The rate of condensation is determined by _________________________—part of the total atmospheric pressure that is caused by water vapor
3. When vapor pressure is high, the condensation rate is high
4. When the rate of evaporation and rate of condensation are in equilibrium, the air is “_________________________________”
a.) Dew Point: the temperature at which the condensation rate equals the evaporation rate
b.) At temperatures below the dew point, net condensation occurs and liquid water droplets form
B. Absolute Humidity
1. _______________________________ is the mass of water vapor contained in a given volume of air (the actual amount of water vapor in the air)
2. Absolute humidity = mass of water vapor (grams)
Volume of air (cubic meters)
C. Relative Humidity
1. Relative humidity (the more common way to express water vapor in atmosphere) is a ratio of the actual water vapor content of the air to the amount of water vapor needed to reach saturation.
D. Measuring Humidity
1. ______________________________: instrument used to measure humidity
Chapter 21 Objectives:
- Explain how an air mass forms
- List the 4 main types of air masses
- Describe how air masses affect the weather of North America
- Compare the characteristic weather patterns of cold fronts with those of warm fronts
- Describe the development of hurricanes, thunderstorms, and tornadoes
- Identify 4 instruments that measure lower-atmospheric weather conditions
- Describe how scientists measure conditions in the upper atmosphere
- Explain how computers help scientists understand weather
- Explain how weather stations communicate weather data
- Explain how a weather map is created, and how computer models help meteorologists forecast the weather
Ch. 21-1 Air Masses page 571
I. How Air Moves
A. Air moves from areas ____________ pressure to areas of low pressure
B. Pressure and temperature differences on Earth’s surface creates wind belts that are influenced by the __________________________, which occurs when winds are deflected by Earth’s rotation
C. Air masses
1. __________________________- large bodies of air throughout which temperature and moisture content are similar
2. If air remains stationary or moves slowly over a uniform region, it takes on the characteristic temperature and humidity of that region
D. Types of Air Masses
1. Classified according to their source regions, which are determined by the _____________________ and _____________________ of the air masses
2. Cold Air Masses are ____________________
3. Warm air masses are ______________________
4. Masses that form over oceans are called maritime (moist)
5. Masses that form over land are continental (dry)
a.) Continental Air Masses: continental polar (cP) and continental tropical (cT)
--cP is _________________________________
-- cT is ________________________________
b.) Maritime Air Masses: maritime polar (mP) and maritime tropical (mT)
-- mP is _______________________________
-- mT is _________________________________
II. 21-2 Fronts page 575
A. A cool air mass is dense and does not mix with the less-dense air of a warm air mass. Thus, a boundary called a front, forms between air masses.
B. Types of Fronts
1. _________________________- when a cold air mass overtakes a warm air mass; moving cold air lifts the warm air
a.) Storms formed along a cold front are usually ____________________ and sometimes violent
b.) A slow-moving cold front typically produces weaker storms and lighter precipitation
2. _______________________- a warm air mass overtakes a cold air mass
a.) Clouds may extend far ahead of the base
b.) Generally produces precipitation over a _______________ area and may occasionally cause violent weather
3. _________________________________- a front at which air masses move either very slowly or not at all
a.) Weather produced is similar to that of a warm front
4.) ___________________________ usually forms when a fast-moving cold front overtakes a warm front and lifts the warm air off the ground completely
C. Severe Weather
- Type of weather that may cause severe property damage or loss of lives
1. Thunderstorms- usually a brief, heavy storm that consists or rain, strong winds, lightning and thunder
a.) during a thunderstorm, clouds discharge electricity in the form of lightning. The upper part of the cloud usually carries a ________________ charge and the lower part carries a ____________ charge. Lighting is a huge spark that travels within the cloud or between the cloud and the ground, to equalize the _____________________________ charges
b.) 3 stages: Cumulus stage, _____________________________, dissipating stage
2. ____________________________- a severe storm that develops over tropical oceans and whose strong winds of more than 120 km/h spiral in toward the intensely low-pressure storm center
a.) with a diameter of 400-800 km hurricanes are the most destructive storms that occur on Earth. Hurricanes cause rising sea level with large waves, called a ______________________
b.) Saffir-Simpson scale- 5 categories based on central pressure, wind speed, and storm surge. Category 1 causes the least damage; Category 5 causes the most damage.
c.) A hurricane begins over warm water when warm, moist air condenses and a large amount of energy in the form of latent heat is released. This heat increases the strength of the rising air.
d.) _____________________: heat energy that is absorbed or released during a phase change
e.) Hurricane Katrina- in August of 2005 this devastating hurricane swept through New Orleans was a category 5 on the Saffir-Simpson scale.
3.) Tornadoes- shortest-lived severe storms, tornadoes are destructive, rotating column of air that has a very high wind speeds and that may be visible as a ______________________ cloud.
a.) Forms when a thunderstorm meets high-altitude, horizontal winds which cause the rising air in the thunderstorm to rotate. A storm cloud may develop a narrow, funnel-shaped, rapidly spinning extension that reaches ___________________________
III. 21-3 Weather Instruments
- Meteorologists measure atmospheric pressure, humidity, temperature, wind speeds, and precipitation to forecast weather patterns
A.) _________________________- instrument that measures and indicates temperature
1. Common type uses mercury or alcohol in a sealed in a glass tube to indicate temperature
B.) ________________________- measures atmospheric pressure; changes in air pressure affect air masses at certain locations
C.) _________________________________- used to measure wind speed
D.) Wind vane- determines the direction of the wind
E.) Scientists use several instruments to measure conditions in the upper atmosphere, to obtain a better understanding of local and global weather patterns such as
1. Radar, weather satellites, and computers
IV. 21-4 Forecasting the Weather
-weather observers at stations around the world report weather conditions frequently. Weather stations around the world exchange the weather information they have collected.
A. Data weather stations collect is transferred onto ______________________. To communicate weather data on a weather map, meteorologists use ___________________ and colors understood my meteorologists around the world.
1. Weather Symbols- clusters of meteorological symbols show weather conditions at the locations of weather stations
a.) these clusters of symbols are called a ______________________- a pattern of meteorological symbols that represents the weather at a particular observing station and that is recorded on a weather map
b.) example on page 588
2. Plotting Temperature and Pressure
a.) __________________________- lines that connect points of equal temperature
b.) __________________________- lines that connect points of equal atmospheric pressure
c.) how closely or widely the lines are spaced indicated changes in pressure and wind speeds
d.) centers marked with an “H” represent high pressure, centers with an “L” represent low pressure
e.) areas of precipitation are commonly marked with colors or symbols
B. Weather Forecasts
- by following the progress of weather systems, meteorologists can forecast the weather
1. __________________________ and satellite images supply important information, such as intensity and precipitation. Meteorologists input these data into computers to create weather models.
2. Types of Forecasts
a.) Nowcasts- mainly use radar and enable forecasters to focus on timing precipitation and tracking severe weather
b.) ______________________________- predict weather conditions for a 48 hour period
c.) Extended Forecasts- look ahead for ______________days
d.) Long-range Forecasts- look ahead at least 7 days and may cover monthly and seasonal periods
e.) accurate weather forecasts can be made for 0-5 days, but accuracy _________________________with each day
3. Severe Weather Watches and Warnings
a.) a Watch is issued when the conditions are ideal for ___________________
b.) ________________________ is given when severe weather has been spotted or is expected within 24 hours
Chapter 22 Objectives:
- Identify 2 major factors used to describe climate
- Explain how latitude determines the amount of solar energy received on Earth
- Describe how the different rates at which land and water are heated affect climate
- Explain the effects of topography on climate
- Describe the 3 types of tropical climates
- Describe the 5 types of middle-latitude climates and 3 types of polar climates
- Explain why city climates may differ from rural climates
Chapter 22: Factors that Affect Climate page 605
A. ________________________: the weather conditions for an area over a long period of time
1. Latitude
a.) Different latitudes on Earth receive different amounts of solar energy- which determines the temperature and wind patterns of an area, which influence the average annual temperature and precipitation
b.) The higher the latitude of an area is, the _____________________ the angle at which the sun’s rays hit the Earth and the smaller the amount of ___________________________ received by the area
c.) Earth’s axis is also a factor, since the angle at which sun’s rays hit an area changes as Earth orbits the sun
2. Topography
a.) ________________________: surface features of the land. Features such as mountains can control the flow of air through a region.
b.) _________________________: when a moving air mass encounters a mountain range, the air mass rises, cools, and loses most of its moisture through precipitation. The air that flows down the other side is usually _____________ and _____________.
c.) Similar dry, warm winds that flow down the eastern slopes of the Rocky Mountains are called ________________________.
A. Climate Zones
1. Tropical Climates- : ____________ temperatures and _____________ precipitation during at least part of the year
a.) Tropical rain-forest climates- humid and warm; Central Africa, Central America and Southeast Asia
b.) Tropical desert climates- very little precipitation
c.) Savanna climates- open grasslands that have clumps of drought-resistant shrubs see table on page 611
2. _____________________________ – a climate that has an average maximum temperature below 18 ° C in the coldest month and an average minimum temperature above 10° C in the warmest month
a.) Marine west coast climates- small annual temp range and frequent rainfall throughout the year – Pacific Northwest of United States
b.) __________________- dry climates that receive less than 40 cm of precipitation a year. Great Plains of U.S
c.) Humid Continental climate- high annual precipitation and large temperature range between summers and winters – in northeast U.S.
d.) Humid Subtropical climate- high annual precipitation, in the southeast U.S
e.) _______________________-_______- mild climate that has a small temperature range between summer and winter – named for Mediterranean Sea between Africa and Europe, also located along coast of central and southern CA
3. _________________________________- characterized by average temperatures that are near or below freezing
a.) Subarctic climate- largest annual temperature range
b.) ___________________________- smaller annual temp range than subarctic but has a colder climate
c.) Polar Icecap climate- most of the land surface and much of the ocean are covered in thick sheets of ice year round. The average temperature never rises above __________________________
4. Effects of Large Bodies of Water
a.) Large bodies of water, such as _____________________, can influence local climates as well as precipitation