Please copy your homework into your assignment book

Please copy your homework into your assignment book
BEFORE THE BELL RINGS Please copy your homework into your assignment book

End Warm-up What is a weather front?
What are different types of weather fronts you have heard of? This bar timer, will start when anywhere on the slide is clicked. The bar will move from left to right and the word ‘End’ will appear at the end, accompanied by a ‘Deep Gong’ sound. It is possible to change the duration of this timer to any time, by entering the animation settings, and changing the timing for ‘rectangle 3’. Note the time has to be entered as a number of seconds – so if you want 2mins & 30secs – this is entered as 150 (60X = 150). End

Thursday, January 12, 2017 Warm-up (collecting these today)
Review Air Masses and Fronts Review game Homework: Midterm Exam Review due 1/17

Air Masses: A large body of air that has the same properties as the surface over which it forms (source region). Example An air mass that forms over water will have higher humidity than an air mass that forms over land.

Air Masses: Air Masses come from latitudes of high pressure (30 and 90) due to sinking air hitting the ground and spreading out. Air mass Weather is CONSTANT! The leading edge of an air mass (FRONT) causes our day to day weather change.

Air Mass Identification
Air masses are named for the region over which they form. (Source Region) Moisture content and Temperature! Identification: Cold = Polar Warm = Tropical Dry = Continental Humid = Maritime

Types of Air Masses There are five (5) types of air masses:
1. Continental Arctic (cA) 2. Continental polar (cP) 3. Maritime polar (mP) 4. Maritime tropical (mT) 5. Continental Tropical (cT)

Continental Arctic (cA):
1. Extremely cold temperatures and very little moisture. 2. These usually originate north of the Arctic Circle. 3. cA air masses affect Canada and occasionally the USA during winter.

Continental polar (cP):
1. Cold and dry, but not as cold as Arctic air masses. 2. These form south of the Arctic circle and often dominate the weather picture across the North central and Eastern U.S. during winter. 3. cP masses do form during the summer, but usually influence only the northern USA. 4. These air masses are responsible for bringing clear and pleasant weather during the summer to the North.

Maritime polar (mP): 1. Cool and humid. 2. mP air masses form over the northern Atlantic and the northern Pacific oceans. 3. They most often influence the Pacific Northwest and the New England States. . 4. mP air masses can form any time of the year and are not as cold as cP air masses.

Maritime tropical (mT):
1. Warm and humid! 2. mT air masses are most common across the eastern and central U.S. and originate over the warm waters of the Southern Atlantic and the Gulf of Mexico. 3.These air masses can form year round, but they are most prevalent across the U.S. during summer. 4. Maritime tropical air masses are responsible for the hot, humid days of summer.

Continental Tropical (cT):
1. Hot and very dry. 2. cT usually form over the Desert Southwest and northern Mexico during summer. 3. cT can bring record heat to the Plains and the Mississippi Valley during summer, but they usually do not make it to the East and the Southeast during winter.

WEATHER FRONTS Chapter 12 notes

FRONTS Front: A boundary separating any contrasting air masses (cold air mass/warm air mass). The leading edge of an air mass! The warm air mass is always pushed up by the cooler air mass. (FRONTAL LIFTING!!!) Due to warm moist air being pushed up, storms and precipitation often occur at front.

Severity of Weather The more intense the Frontal Lifting (Updrafts):
The lower the pressure The more severe weather conditions Depends on Diversity of Air Masses and Speed of Air Mass movement.

FRONTS Four (4) Types of Fronts 1. Cold Front 2. Warm Front
3. Stationary Front 4. Occluded Front

COLD FRONT On a weather map, a cold front is always represented by a line with blue triangles The arrows tell where the warm air is and the direction the front is moving

COLD FRONT A cold front forms when a cold air mass moves into an area that was covered by a warm air mass. Cold air

COLD FRONT

COLD FRONT CONDITIONS Altocumulus clouds are often seen ahead of a cold front. Cumulonimbus clouds may be found along the front. Cold fronts usually bring high winds, heavy rains, and possible violent weather but only for a short period of time.

COLD FRONT CONDITIONS After the front passes, skies will begin to clear. Winds will shift from the South to the West/Northwest after the front passes.

Weather Phenomenon Prior to the Passing of the Front Contact with the Front After the Passing of the Front Temperature Warm Cooling suddenly Cold and getting colder Atmospheric Pressure Decreasing steadily Leveling off then increasing (Low!!!) Increasing steadily Winds South to southwest Variable and gusty West to northwest Precipitation Threatening Skies Heavy rain or snow, hail sometimes Rapid Dissipation and Clearing Clouds Ci, Cc, Ac, Cu Cumulus and cumulonimbus Cu, Ac, Cc, Ci

WARM FRONT On a weather map, a warm front is always represented by a line with red semi-circles. The semi-circles tell where the cold air is and the direction the front is moving

WARM FRONT A warm front forms when a warm air mass moves into an area that was covered by a cold air mass. Warm air

WARM FRONT

WARM FRONT CONDITIONS The first sign that a warm front is approaching is the appearance of cirrus clouds. As the front moves closer, cirrostratus clouds move in followed by altostratus, and finally, thick stratus or nimbostratus clouds fill the sky. Warm fronts usually bring light to moderate rain over a large area for several days.

WARM FRONT CONDITIONS After the front passes, skies will generally clear although some cumulus or altocumulus clouds are present. Winds will shift from the South to West after the front passes.

Weather Phenomenon Prior to the Passing of the Front Contact with the Front After the Passing of the Front Temperature Cool Warming suddenly Warmer then leveling off Atmospheric Pressure Decreasing steadily Low but not as low as a Cold Front Slight rise but not as High as Prior to Front Winds South to southeast Variable South to southwest Precipitation Overcast Conditions Showers, snow, sleet or drizzle Precip. Slowly Tapering off Clouds Cirrus, cirrostratus, altostratus, then stratus Stratus, Nimbostratus Clearing with scattered cumulus clouds

STATIONARY FRONT On a weather map, a stationary front is always represented by a line with red semi-circles on one side and blue triangles on the other.

STATIONARY FRONT Stationary fronts are formed when pressure differences cause the front to stop moving. The condition may last for several days. Weather at a stationary front will be overcast with light wind and light precipitation.

OCCLUDED FRONT On a weather map, an occluded front is always represented by a line with semi- circles and triangles on the same side colored purple

OCCLUDED FRONT Occluded fronts are formed when 2 cold air masses come together and force warm air up between them. The weather at an occluded front is very complex and difficult to predict. However, strong winds and heavy rains often accompany this type of front.

OCCLUDED FRONT

EARTH SCIENCE Geology, the Environment and the Universe
Chapter 13: The Nature of Storms

Thunderstorms Essential Questions Review Vocabulary
SECTION13.1 Thunderstorms Essential Questions How do thunderstorms form? What are the different types of thunderstorms? What is the life cycle of a thunderstorm? Review Vocabulary latent heat: stored energy in water vapor that is not released to warm the atmosphere until condensation occurs

Thunderstorms New Vocabulary
SECTION13.1 Thunderstorms The intensity and duration of thunderstorms depend on the local conditions that create them. New Vocabulary air-mass thunderstorm mountain thunderstorm sea-breeze thunderstorm frontal thunderstorm stepped leader return stroke

SECTION13.1 Thunderstorms Up to thunderstorms are in progress around the world

SECTION13.1 Thunderstorms Both geography and air mass movements make thunderstorms most common in the southeastern United States.

Thunderstorms How thunderstorms form
SECTION13.1 Thunderstorms How thunderstorms form For a thunderstorm to form, three conditions must exist: a source of moisture, lifting of the air mass, and an unstable atmosphere.

SECTION13.1 Thunderstorms Limits to thunderstorm growth TROPOPAUSE

Types of Thunderstorms
SECTION13.1 Thunderstorms Types of Thunderstorms Thunderstorms are often classified according to the mechanism that causes the air mass that formed them to rise. There are two main types of thunderstorms: air-mass and frontal.

SECTION13.1 Thunderstorms Types of Thunderstorms Air-mass thunderstorms When air rises because of unequal heating of Earth’s surface beneath one air mass, the thunderstorm is called an air-mass thunderstorm. There are two kinds of air-mass thunderstorms.

SECTION13.1 Thunderstorms Types of Thunderstorms Air-mass thunderstorms Mountain thunderstorms occur when an air mass rises by orographic lifting, which involves air moving up the side of a mountain.

SECTION13.1 Thunderstorms Types of Thunderstorms Air-mass thunderstorms Sea-breeze thunderstorms are local air-mass thunderstorms that occur because land and water store and release thermal energy differently.

SECTION13.1 Thunderstorms Types of Thunderstorms Frontal thunderstorms Frontal thunderstorms are produced by advancing cold fronts and, more rarely, warm fronts.

Thunderstorm Development
SECTION13.1 Thunderstorms Thunderstorm Development A thunderstorm usually has three stages: the cumulus stage, the mature stage, and the dissipation stage. The stages are classified according to the direction the air is moving.

SECTION13.1 Thunderstorms Lightning is the transfer of electrical charge caused by the rapid rushes of air in a cumulonimbus cloud.

Thunderstorms Lightning Facts
SECTION13.1 Thunderstorms Lightning Facts A lightning bolt heats the surrounding air to about 30,000C, about five times hotter than the surface of the Sun. Lightning natural creates Ozone. Lightning kills 60 people a year. The thunder you hear is the sound produced as this superheated air rapidly expands and contracts.

Thunderstorms in the United States are most common in the Midwest.
SECTION13.1 Section Check Thunderstorms in the United States are most common in the Midwest. a. true b. false

SECTION13.1 Section Check A mature thunderstorm has a region of updraft and a region of downdraft. a. true b. false

SECTION13.1 Section Check What is the difference between air-mass thunderstorms and frontal thunderstorms? Answer: Air-mass thunderstorms form as a result of uplift of air within one air mass. Frontal thunderstorms form as a result of uplift of air along frontal boundaries.

Severe Weather Essential Questions
SECTION13.2 Severe Weather Essential Questions Why are some thunderstorms more severe than others? What are the dangers of severe weather? How do tornadoes form?

Severe Weather Review Vocabulary
SECTION13.2 Severe Weather All thunderstorms produce wind, rain, and lightning, which can have dangerous and damaging effects under certain circumstances. Review Vocabulary air mass: large body of air that takes on the characteristics of the area over which it forms

Severe Weather New Vocabulary supercell downburst tornado
SECTION13.2 Severe Weather New Vocabulary supercell downburst tornado Enhanced Fujita Tornado Damage scale Audio will need to change for EFTD scale (was Fujita Tornado intensity scale).

Severe Weather Severe Thunderstorms Supercells
SECTION13.2 Severe Weather Severe Thunderstorms Supercells Severe thunderstorms can develop into self-sustaining, extremely powerful storms called supercells. These furious storms can last for several hours and can have updrafts as strong as 240 km/h.

SECTION13.2 Severe Weather Severe Thunderstorms Supercells An anvil-shaped cumulonimbus cloud is characteristic of many severe thunderstorms.

Severe Weather Strong Winds
SECTION13.2 Severe Weather Strong Winds Violent downdrafts that are concentrated in a local area are called downbursts. Based on the size of the area they affect, downbursts are classified as either macrobursts or microbursts.

SECTION13.2 Severe Weather Hail Hail is precipitation in the form of balls or lumps of ice. It forms because of two characteristics common to thunderstorms.

SECTION13.2 Severe Weather Hail For hail to form, water droplets rise to the heights of a cumulonimbus cloud where the temperature is below freezing, encounter ice pellets, and freeze on contact with the pellets, which causes the ice pellets to grow larger.

SECTION13.2 Severe Weather Hail The second characteristic that allows hail to form is an abundance of strong updrafts and downdrafts moving side by side within a cloud.

Severe Weather Tornadoes
SECTION13.2 Severe Weather Tornadoes A tornado is a violent, whirling column of air in contact with the ground. When a tornado does not reach the ground, it is called a funnel cloud.

Severe Weather Tornadoes Development of tornadoes
SECTION13.2 Severe Weather Tornadoes Development of tornadoes A tornado forms when wind speed and direction change suddenly with height, a phenomenon called wind shear. Although tornadoes rarely exceed 200 m in diameter and usually last only a few minutes, they can be extremely destructive.

Severe Weather Please click the image above to view the video.
SECTION13.2 Severe Weather Please click the image above to view the video.

Severe Weather Tornadoes Tornado classification
SECTION13.2 Severe Weather Tornadoes Tornado classification The Enhanced Fujita Tornado Damage scale, which ranks tornadoes according to their destruction and estimated wind speed, is used to classify tornadoes.

SECTION13.2 Severe Weather Please click the image above to view the interactive table.

Severe Weather Tornadoes Tornado distribution
SECTION13.2 Severe Weather Tornadoes Tornado distribution Most tornadoes—especially violent ones—form in the spring during the late afternoon and evening, when the temperature contrasts between polar air and tropical air are the greatest. This type of large temperature contrast occurs most frequently in the central United States.

SECTION13.2 Severe Weather Tornadoes Tornado distribution Many of the more than 1000 tornadoes that touch down in the United States each year occur in a region called “Tornado Alley,” which extends from northern Texas through Oklahoma, Kansas, and Missouri.

Severe Weather Tornadoes Tornado safety
SECTION13.2 Severe Weather Tornadoes Tornado safety If you are caught in a tornado, take shelter in the southwest corner of a basement, a small downstairs room or closet, or a tornado shelter.

SECTION13.2 Section Check The strongest thunderstorms develop under highly stable atmospheric conditions. a. true b. false

SECTION13.2 Section Check Which type of precipitation requires strong updrafts and downdrafts to exist side by side in a cloud? a. rain b. snow c. hail d. sleet

Section Check How do tornadoes form?
Answer: The rotation of a tornado begins as a result of wind shear, wind at different levels of the atmosphere blowing in different directions or at different speeds. The horizontal rotation is then tilted to a vertical position by thunderstorm updrafts. A tornado forms if the rotating column extends to the ground.

Tropical Storms Essential Questions How do tropical cyclones form?
SECTION13.3 Tropical Storms Essential Questions How do tropical cyclones form? What is the life cycle of a tropical cyclone? What are the dangers associated with hurricanes?

Tropical Storms Review Vocabulary
SECTION13.3 Tropical Storms Normally peaceful, tropical oceans are capable of producing one of Earth’s most violent weather systems—the tropical cyclone. Review Vocabulary Coriolis effect: caused by Earth’s rotation, moving particles, such as air, are deflected to the right north of the equator, and to the left south of the equator

Tropical Storms New Vocabulary tropical cyclone
SECTION13.3 Tropical Storms New Vocabulary tropical cyclone eye eyewall Saffir-Simpson Hurricane Wind scale storm surge

Overview of Tropical Cyclones
SECTION13.3 Tropical Storms Overview of Tropical Cyclones During summer and fall, the tropics experience conditions ideal for the formation of large, rotating, low-pressure tropical storms called tropical cyclones.

SECTION13.3 Tropical Storms Overview of Tropical Cyclones Cyclone location Favorable conditions for cyclone formation exist in all tropical oceans except the South Atlantic Ocean and the Pacific Ocean off the west coast of South America.

Tropical Storms Please click the image above to view the video.
SECTION13.3 Tropical Storms Please click the image above to view the video.

SECTION13.3 Tropical Storms Overview of Tropical Cyclones Cyclone formation Tropical cyclones require two basic conditions to form: an abundant supply of warm ocean water and some sort of mechanism to lift warm air and keep it rising.

SECTION13.3 Tropical Storms Overview of Tropical Cyclones Cyclone formation The first indication of a building tropical cyclone is a moving tropical disturbance. When a disturbance over a tropical ocean acquires a cyclonic circulation around a center of low pressure, it has reached the developmental stage and is known as a tropical depression.

SECTION13.3 Tropical Storms Overview of Tropical Cyclones Cyclone formation When wind speeds around the low-pressure center of a tropical depression exceed 62 km/h, the system is called a tropical storm. If air pressure continues to fall and winds around the center reach at least 119 km/h, the storm is officially classified as a cyclone.

SECTION13.3 Tropical Storms Overview of Tropical Cyclones Cyclone formation Once winds reach at least 119 km/h, another phenomenon occurs—the development of a calm center of the storm called the eye. The eye of the cyclone is often 30 to 60 km of calm weather and blue sky.

SECTION13.3 Tropical Storms Overview of Tropical Cyclones Cyclone formation The strongest winds in a hurricane are usually concentrated in the eyewall—a tall band of strong winds and dense clouds that surrounds the eye.

SECTION13.3 Tropical Storms Overview of Tropical Cyclones Cyclone formation A hurricane will last until it can no longer produce enough energy to sustain itself. This usually happens when the storm has moved either over land or over colder water.

Visualizing Cyclone Formation
SECTION13.3 Tropical Storms Visualizing Cyclone Formation Like most storms, cyclones begin with warm moist air rising.

Tropical Storms Please click the image above to view the video.
SECTION13.3 Tropical Storms Please click the image above to view the video.

SECTION13.3 Tropical Storms Overview of Tropical Cyclones Tropical cyclone movement Like all large-scale storms, tropical cyclones move according to the wind currents that steer them.

Tropical Storms Hurricane Hazards
SECTION13.3 Tropical Storms Hurricane Hazards The Saffir-Simpson Hurricane Wind scale classifies hurricanes according to wind speed, which implies potential for flooding and potential for property damage.

Tropical Storms Hurricane Hazards Damage
SECTION13.3 Tropical Storms Hurricane Hazards Damage Hurricanes can cause extensive damage, particularly along coastal areas, which tend to be where human populations are the most dense.

Tropical Storms Hurricane Hazards Winds
SECTION13.3 Tropical Storms Hurricane Hazards Winds Much of the damage caused by hurricanes is associated with violent winds.

Tropical Storms Hurricane Hazards Storm surge
SECTION13.3 Tropical Storms Hurricane Hazards Storm surge A storm surge occurs when hurricane-force winds drive a mound of ocean water toward coastal areas where it washes over the land.

Tropical Storms Hurricane Hazards Hurricane advisories and safety
SECTION13.3 Tropical Storms Hurricane Hazards Hurricane advisories and safety The National Hurricane Center issues a hurricane warning at least 36 hours before a hurricane is predicted to strike. Awareness, combined with proper safety precautions, has greatly reduced death tolls associated with hurricanes in recent years.

At what latitudes do tropical cyclones usually form?
SECTION13.3 Section Check At what latitudes do tropical cyclones usually form? a. between 0 and 5 b. between 5 and 30 c. between 30 and 50 d. between 50 and 70

What weather condition usually exists within the eye of a hurricane?
SECTION13.3 Section Check What weather condition usually exists within the eye of a hurricane? a. high wind b. calm wind c. tornadoes d. lightning

What is the source of a hurricane’s energy?
SECTION13.3 Section Check What is the source of a hurricane’s energy? Answer: A hurricane’s energy comes from the warm water over which it develops. As ocean water evaporates, some heat is taken from the ocean. The water vapor then rises high into the atmosphere. The heat that was taken from the ocean is released to the atmosphere as the water vapor condenses.

Recurrent Weather Essential Questions
SECTION13.4 Recurrent Weather Essential Questions What are the problems associated with recurring weather patterns? What atmospheric events cause recurring weather patterns? How do heat waves and cold waves differ?

Recurrent Weather Review Vocabulary
SECTION13.4 Recurrent Weather Even a relatively mild weather system can become destructive and dangerous if it persists for long periods of time. Review Vocabulary Fahrenheit scale: a temperature scale in which water freezes at 32 and boils at 212

Recurrent Weather New Vocabulary drought heat wave cold wave
SECTION13.4 Recurrent Weather New Vocabulary drought heat wave cold wave windchill index

Recurrent Weather Floods
SECTION13.4 Recurrent Weather Floods An individual thunderstorm can unleash enough rain to produce floods, and hurricanes also cause torrential downpours, which result in extensive flooding. Floods can also occur when weather patterns cause even mild storms to persist over the same area.

Recurrent Weather Floods
SECTION13.4 Recurrent Weather Floods Low-lying areas are most susceptible to flooding, making coastlines particularly vulnerable to storm surges during hurricanes. Rivers in narrow-walled valleys can rise rapidly, creating high-powered and destructive walls of water.

Recurrent Weather Droughts
SECTION13.4 Recurrent Weather Droughts Droughts are extended periods of well-below-average rainfall. Droughts are usually the result of shifts in global wind patterns that allow large, high-pressure systems to persist for weeks or months over continental areas.

Recurrent Weather Droughts
SECTION13.4 Recurrent Weather Droughts Because the sinking air prevents humid air from rising, condensation cannot occur, and drought sets in until global patterns shift enough to move the high-pressure system.

Recurrent Weather Droughts Heat waves
SECTION13.4 Recurrent Weather Droughts Heat waves An unpleasant side effect of droughts often comes in the form of heat waves, which are extended periods of above-average temperatures. Heat waves can be formed by the same high-pressure systems that cause droughts.

Recurrent Weather Droughts Heat waves
SECTION13.4 Recurrent Weather Droughts Heat waves Because of the dangers posed by a combination of heat and humidity, the National Weather Service (NWS) routinely reports the heat index. The heat index assesses the effect of the body’s difficulty in regulating its internal temperature as relative humidity rises.

SECTION13.4 Recurrent Weather Please click the image above to view the interactive table.

Recurrent Weather Cold Waves
SECTION13.4 Recurrent Weather Cold Waves The opposite of a heat wave is a cold wave, which is an extended period of below-average temperatures. Cold waves are also brought on by large, high-pressure systems. However, cold waves are caused by systems of continental polar or arctic origin.

SECTION13.4 Recurrent Weather Cold Waves Because of the location and the time of year in which they occur, winter high-pressure systems are much more influenced by the jet stream than are summer high-pressure systems.

SECTION13.4 Recurrent Weather Cold Waves The winter location of the jet stream can remain essentially unchanged for days or even weeks. This means that several polar high-pressure systems can follow the same path and subject the same areas to continuous numbing cold.

Recurrent Weather Cold Waves Windchill index
SECTION13.4 Recurrent Weather Cold Waves Windchill index The effects of cold air on the human body are magnified by wind. Known as the windchill factor, this phenomenon is measured by the windchill index.

Recurrent Weather Cold Waves Windchill index
SECTION13.4 Recurrent Weather Cold Waves Windchill index The windchill chart was designed to show the dangers of cold and wind.

SECTION13.4 Section Check The temperature is 0F and the wind speed is 30 miles per hour. What is the windchill? a. –5F b. –10F c. –26F d. –58F Replace table? (S/b Windchill)

What happens to air at the center of a high-pressure system?
SECTION13.4 Section Check What happens to air at the center of a high-pressure system? a. It sinks and water vapor condenses. b. It sinks and water vapor resists condensation. c. It rises and water vapor condenses. d. It rises and water vapor resists condensation.

What conditions result in extensive flooding?
SECTION13.4 Section Check What conditions result in extensive flooding? Possible answer: The most extensive flooding occurs as a result of heavy and persistent rain, saturated soil, and low-lying ground.

The Nature of Storms Earth Science Online Study Guide
CHAPTER13 The Nature of Storms Resources Earth Science Online Study Guide Chapter Assessment Questions Standardized Test Practice

SECTION13.1 Thunderstorms Study Guide The intensity and duration of thunderstorms depend on the local conditions that create them. The cumulus stage, the mature stage, and the dissipation stage comprise the life cycle of a thunderstorm. Clouds form as water is condensed and latent heat is released.

SECTION13.1 Thunderstorms Study Guide Thunderstorms can be produced either within air masses or along fronts. From formation to dissipation, all thunderstorms go through the same stages. Lightning is a natural result of thunderstorm formation.

SECTION13.2 Severe Weather Study Guide All thunderstorms produce wind, rain, and lightning, which can have dangerous and damaging effects under certain circumstances. Intense rotating updrafts are associated with supercells. Downbursts are strong winds that result in damage associated with thunderstorms.

SECTION13.2 Severe Weather Study Guide Hail is precipitation in the form of balls or lumps of ice that accompany severe storms. The worst storm damage comes from a vortex of high winds that moves along the ground as a tornado.

SECTION13.3 Tropical Storms Study Guide Normally peaceful, tropical oceans are capable of producing one of Earth’s most violent weather systems—the tropical cyclone. Tropical cyclones rotate counterclockwise in the northern hemisphere. Tropical cyclones are also known as hurricanes and typhoons.

SECTION13.3 Tropical Storms Study Guide Tropical cyclones go through the same stages of formation and dissipation as other storms. Tropical cyclones are moved by various wind systems after they form. The most dangerous part of a tropical cyclone is the storm surge. Hurricane alerts are given at least 36 hours before the hurricane arrives.

SECTION13.4 Recurrent Weather Study Guide Even a relatively mild weather system can become destructive and dangerous if it persists for long periods of time. Too much heat and too little precipitation causes droughts. Too little heat and a stalled jet stream can cause weeks of cold weather in an area.

SECTION13.4 Recurrent Weather Study Guide Heat index estimates the effect on the human body when the air is hot and the humidity is high. Cold index tells how wind, humidity, and temperature affect your body in winter. Windchill is a factor used to warn about the effect of cold air and wind on the human body.

CHAPTER13 The Nature of Storms Chapter Assessment Which weather event is often related to the presence of persistent high pressure over a region? a. a flood b. a drought c. a tornado d. a blizzard

CHAPTER13 The Nature of Storms Chapter Assessment Which type of movement describes the air flow in the eyewall of a hurricane? a. counterclockwise upward spiral b. clockwise upward spiral c. counterclockwise downward spiral d. clockwise downward spiral

CHAPTER13 The Nature of Storms Chapter Assessment Why do people feel less comfortable on a hot day when the humidity is high? a. The air is less dense. b. The air moves less. c. Less evaporation occurs. d. Less precipitation occurs.

CHAPTER13 The Nature of Storms Chapter Assessment Which type of thunderstorm could form as a result of the air circulation shown? a. mountain thunderstorm b. sea-breeze thunderstorm c. cold-front thunderstorm d. warm-front thunderstorm

CHAPTER13 The Nature of Storms Chapter Assessment What hazards do hurricanes cause when they make landfall? Possible answer: Hurricanes making landfall bring high wind, tornadoes, and sometimes severe lightning. Storm surge causes flooding along the coast, and heavy rain causes flooding inland.

CHAPTER13 The Nature of Storms Standardized Test Practice What forms as superheated air expands and produces a shock wave? a. lightning b. thunder c. tornado d. microburst

The Nature of Storms What is the Saffir-Simpson scale?
CHAPTER13 The Nature of Storms Standardized Test Practice What is the Saffir-Simpson scale? a. a scale for classifying tornadoes b. a scale for classifying hurricanes c. a scale for classifying thunderstorms d. a scale for classifying lightning

CHAPTER13 The Nature of Storms Standardized Test Practice On which side of a northern hemisphere tropical cyclone does the wind blow from the south? a. north side b. west side c. south side d. east side

CHAPTER13 The Nature of Storms Standardized Test Practice How is the life cycle of a supercell thunderstorm similar to the life cycle of a hurricane? Possible answer: Both storms form from energy supplied by rising moist air, and both storms dissipate when the supply of rising moist air is cut off.

The Nature of Storms Why do hailstones consist of concentric layers?
CHAPTER13 The Nature of Storms Standardized Test Practice Why do hailstones consist of concentric layers?

CHAPTER13 The Nature of Storms Standardized Test Practice Possible answer: The layers form as hailstones are tossed in a thunderstorm by strong updrafts. A new layer of ice is added each time the hailstone moves into a level of supercooled water droplets. These water droplets exist at temperatures that are well below the normal freezing point of water and so change to ice as soon as they come into contact with the hailstone.

SECTION13.2 Severe Weather Severe Thunderstorms Supercells Severe thunderstorms can develop into self-sustaining, extremely powerful storms called supercells. These furious storms can last for several hours and can have updrafts as strong as 240 km/h.