# Chapter 13 Global Weather Dynamics

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Chapter 13 Global Weather Dynamics

Weather Dynamics involves trying to understand why the cloud’s, air masses and water on the Earth are in constant motion. We need to consider the Earth’s energy balance and the affect of the Sun’s energy on all of the above factors. We should be able to explain the weather patterns we see and predict what those weather patterns will do in the future. We will also see how the above factors create extreme weather conditions in certain parts of the world, like hurricanes, cyclones , blizzards and flooding. Weather facts and trivia Website

13.1 Comparing Weather and Climate
The main components that influence weather are the atmosphere, the land forms, and water in its various forms (solid,liquid and vapor). 70% of the Earth is covered by water and the remainder forms the continents. The atmosphere above the Earth contains water vapor, dust and chemicals all of which effect the weather on Earth.

Weather is the set of environmental conditions encountered from day to day.
Climate is the set of environmental conditions averaged over many years. Weather patterns and climate can vary greatly on Earth. There are useful boundaries which help us determine the type of weather or climate we may encounter as we travel the world.

Latitude and Longitude Website

Assignment : Start collecting 5 day weather forecasts so we can analyze them at a later date Do Understanding Concepts 1-9 pg 503

13.2 Earth’s Energy Balance
Almost all the energy on Earth comes from the Sun. The energy from the Sun is used by plants to grow, and the land ,water and air wouldn’t stay warm enough for us to survive without it. This energy is in the form of electromagnetic radiation and it comes in different forms. Energy can be transferred from one place to another by 4 methods: Radiation Conduction Convection Advection Energy Transfer Methods website

Radiation – is the transfer of energy by the means of waves
Radiation – is the transfer of energy by the means of waves. These wave do not need a medium like water or air to pass through. This is why they can travel through the vacuum of outer space to reach us from the Sun. Visible light is one of the forms of radiation that reaches us from the Sun as well as infrared radiation, ultraviolet radiation and X-rays.

The other methods of energy transfer require some medium or particles of matter.
Conduction – is the transfer of energy through the collision of particles. This occurs most easily in metals such as steel but also it occurs on the Earth’s surface, including rock, sand soil, and water

Convection and Advection – are the transfer of energy by movements of particles of liquid like water in the atmosphere. Convection transfers energy vertically. Advection transfers energy horizontally.

Since weather systems depend on the movement of particles in the atmosphere and in the oceans we will often only use these 2 forms of energy transfer to understand weather systems

Solar radiation is scattered or absorbed when it hits the Earth’s atmosphere.
For the radiation that reflects off the atmosphere and the surface features of Earth, the portion reflected depends on the albedo of the material. Clean snow has a high albedo; it reflects a large portion of the incoming energy. Black soil has a low albedo; it absorbs more energy than it reflects.

Any object or material that absorbs energy and becomes warmer is called a heat sink.
Water is a good heat sink. Even though water has a high albedo, when solar energy hits water, the water begins to move-this is convection activity-and energy is passed down into the water.

An important property of all substances is their heat capacity or how much heat a substance requires to increase its temperature. Poor heat sinks have a low heat capacity and good heat sinks have a high heat capacity.

Conduction or convection? Good heat sink or bad heat sink?
Ice and coke Stove Element Conduction or convection? Good heat sink or bad heat sink? High heat capacity or low heat capacity?

Understanding Concepts 1-10 pg 507
Assignment : Understanding Concepts 1-10 pg 507 View Video – Dimming of the Sun (1hr) Use These Viewing Ideas Dimming The Sun Lab Students will set up pan evaporation devices and for four uninterrupted days will measure and record pan evaporation amounts, air temperature, relative humidity, wind speed, solar radiation, and precipitation. Appendix 4.4 Connecting Mathematics to the Atmosphere

13.3 Reasons for the Seasons

Our changing seasons and the resulting weather changes depend upon the Earth’s revolution around the sun combined with the tilt of the earth’s axis. Fig. 1, p Copy This

Summer Solstice -June 21 -occurs when the northern hemisphere has summer and it is winter in the southern hemisphere. -The earth is tilted towards the sun. -The Sun is directly over the Tropic of Cancer. -The longest day of the year in the northern hemisphere.

Winter Solstice-December 21
-winter in the northern hemisphere and it is summer in the southern hemisphere. -The earth is tilted away from the sun. -The sun is directly over the Tropic of Capricorn. -The shortest day of the year in the northern hemisphere.

Autumnal Equinox-September 21
Vernal Equinox -March 21 -spring in the northern hemisphere. -Sun hits the earth at the equator. Equal length day and night. Autumnal Equinox-September 21 -fall in the northern hemisphere. S -Equal length day and night.

Investigation 13.3 Angle of Incidence
Much of Earth’s weather, especially our changing seasons, is caused by Earth’s revolution around the Sun combined with the tilt of the Earth’s axis. With this investigation we will explore how the amount of energy received at a surface depends on the angle of the light rays (solar energy) striking the surface. Objectives To determine the effect of the earth's tilt on the amount of incoming solar radiation throughout the year. To understand the reason for the changes in seasons. Seasons Animation and Informationwebsite Seasons Animation website

PROCEDURE 1. Have a student hold a flashlight in the center of the room and beam like the sun. 2. Take the tilted globe and walk around the light bulb to simulate the earth's orbit around the sun. Important: Always tilt the "earth" toward a specific wall of the classroom. It is scientifically incorrect to always tilt it toward or away from the "sun".

QUESTIONS Using the knowledge you have gained in "Angle of Incidence", how intense (bright) is the light at your school on December 21? On March 21? On June 21? On September 21?  . What does your answer in #1-4 say about light hitting the earth from the sun throughout the year?  What factors determine how much light hits a point on the earth on a clear day? If the earth were not tilted on its axis, would the amount of sunlight that hit a given point on the earth's surface change from season to season? Explain. What causes the seasons? The earth is closer to the sun in the winter in the Northern Hemisphere than in the summer. Why is it cooler in the winter if the earth is closer to the sun?

13.4 The Atmosphere The atmosphere is the blanket of air and moisture that surrounds the Earth. It is most dense at sea level where the molecules of air are pressed together by the weight of the air above, the atmosphere becomes less dense as the height above sea level increases. Near Earth’s surface the atmosphere is 78% nitrogen, 21% oxygen and small amounts of carbon dioxide, water vapor and argon. Atmospheric Layers and Temperature Animation

Layers of the Atmosphere
Each layer of the atmosphere has its own unique properties like moisture content, temperature and function.

Troposphere The layer closest to the Earth’s surface Up to an altitude of 8 to16 km, thicker at the equator Contains most of the atmosphere’s moisture Responsible for most of our weather systems As the altitude increases the temperature drops Where the troposphere ends is a thin boundary called the tropopause The tropopause contains a little more ozone which helps absorb harmful ultraviolet radiation from the Sun

tropopause

The Stratosphere Just above the tropopause A dry layer between 12 to 50 km thick Contains higher concentrations of ozone that help protect us from ultraviolet radiation Ozone presence explains why the temperature of the stratosphere increases as the altitude increases (absorbs energy) Ozone is poisonous

The Mesosphere -The middle layer of the atmosphere -The temperature drops dramatically -The amount of gases in the atmosphere decreases (density) -50 to 80 km up

The Thermosphere Above the mesosphere Density of the gas molecules is still low but they have much more energy which increases the temperature(no protection from the sun) The high energy radiation from the Sun is absorbed here (X-rays) 80 to 500 km

Also called the Ionosphere because in this layer high energy radiation from the Sun causes particles to become electrically charged ions. The ions produce the Northern and Southern Lights or auroras

The Exosphere The thin outermost layer of the atmosphere At this point you are in outer space because the density of the air has dropped to almost nothing Temperature drops significantly The change in temperature over a distance is called the temperature gradient. The temperature gradient for the troposphere is about – 6 degrees celcius per 1000 m increase in altitude

Atmosphere is important because:
Contains oxygen which supports life Ozone protects us from harmful UV radiation Plays a role in the water cycle Protects us from meteor impacts Helps keep the average temperature within life support range Circulates air to maintain an energy balance on Earth

As altitude increases air pressure decreases
Atmospheric pressure The pressure that air exerts as gravity pulls it toward the center of the Earth As altitude increases air pressure decreases You must consider air pressure in the vertical and the horizontal Atmospheric pressure website

Low Pressure Weather System
Watch What Air Pressure Can Do

Pressure gradient Measure of the amount of atmospheric pressure changes across a set distance Pressure gradients can be both horizontal and vertical Copy Figure 4a and 4b into you notebook. Write a description explaining both figures in your own words

air pressure is measured in units called kiloPascals (1 kiloPascal = 1000 Pascals)
An average student standing on a floor would be able to apply about 100 kPa of pressure on the floor The most common instrument used to measure air pressure is the barometer

Understanding Concepts 1-9 pg 513
Assignment : Understanding Concepts 1-9 pg 513 Assignment : Understanding Concepts 1-4 pg 515 SLA APPENDIX 4.17 Understanding Highs and Lows SLA APPENDIX 4.18 Introduction to Weather Maps and Symbols

13.6 Prevailing Wind Patterns
Of all weather features winds are most important. There are local winds that may affect Killarney and surrounding areas and there are prevailing winds that affect large areas and the weather in those areas.

Earth’s rotation causes anything that moves along its surface, like prevailing winds , to appear to change direction. This apparent change in direction is called the Coriolis effect.

Because of the Coriolis effect prevailing winds in the Northern Hemisphere appear to turn to the right and in the Southern Hemisphere they turn to the left.

The Coriolis Effect Game Website
Coriolis Effect Animation Another Coriolis Effect Animation SLA Appendix 4.7 It Bends Because the Earth Turns

Causes of Prevailing Winds
Prevailing winds are caused by a combination of convection currents and Earth’s eastward rotation. How Prevailing Winds Form Video

Once the warm reaches the tropopause it moves northward
Solar energy strikes the equator directly This creates a convection current and causes the air mass to warm , rise and expand leaving behind an area of low pressure Once the warm reaches the tropopause it moves northward As it moves northward it cools and becomes more dense At about 30 degrees latitude it is dense enough to sink back to the Earth

Air at the surface moves away from this area of high pressure toward the area of low pressure at the equator This moving surface air twists to the right as it moves south causing the northeast tradewinds At 30 degrees latitude some of the descending air is deflected northward along the surface of the Earth away from this area of high pressure to an area of low pressure at about 60 degrees latitude

This moving air warms as it moves along the Earth’s surface and twists to the right causing the mid latitude westerlies At 60 degrees latitude this warm air mass rises causing an area of low pressure Most of this warm moves toward the south once it reaches the tropopause Some of this rising warm air spills north at the tropopause and moves toward the north pole A Jet Stream Animation A Jet Stream Website

As it cools and becomes more dense it will fall back to the earth at the north pole
This cool air mass moves south along the surface of the Earth twisting to the right causing the polar easterlies Jet streams form at 30 and 60 degrees latitude where 2 air masses are colliding. These jet streams always move from west to east at about 7000m altitude

Effects of Prevailing Winds
·        Help distribute large amounts of solar energy from the equator to the colder parts of the world ·        Carry moisture causing rain and snow ·        Rising air is warm and moist and falling air is cool and dry ·        Rising air indicates areas on the Earth where there are rainforests and strong winter storms ·        Falling air indicates areas where there are deserts

Assignment : Complete the diagram of prevailing winds for both the northern and southern hemispheres using the following terms and the key symbols : dry cool air, wet warm air, high pressure area, low pressure area, tropopause, convection currents, polar easterlies, mid latitude westerlies, northeast tradewinds, direction of Earth’s rotation, southeast tradewinds, jet stream  Use BLM World Map (Globe Projection) Appendix 4.11 Each term can be used more than once Understanding Concepts 1-4 pg 519

13.8 The Hydrosphere All of the Earth’s water, both fresh and salt forms, is what we call the hydrosphere. This water can be in the solid,liquid or vapor state. Salt Water 97.5% Fresh Water 2.5% Glaciers and Ice Caps 87.3% Underground Water 12.3% Earth’s Water Resources Lakes 90% Atmosphere 9% Rivers 1% Surface and Atmospheric Water 0.4%

BOTTLES OF WATER Total Contain Salt Water 2200 are full of Ice 310 contain Underground Water 9 contain Lake Water 0.09 of a bottle contains Atmospheric Water of a bottle contains River Water * BOLD IS AVAILABLE DRINKING WATER

Diagram the water cycle using the above terms.
Our weather depends heavily on the water cycle. Terms used in the water cycle are radiation, runoff, ground water, evaporation ( liquid to gas ), sublimation ( solid to gas ), condensation ( gas to solid ), transpiration ( evaporation of water from plant surface ), precipitation ( rain, hail or snow ), freezing ( liquid to solid ), infiltration ( soaking into the soil ). Assignment : Diagram the water cycle using the above terms. Do Understanding Concepts 1-8 pg 524 The Water Cycle website

ice lake

13.9 Major Ocean Currents There is very little land mass at the equator, there is mostly ocean. This is the area of Earth that receives the most direct and intense solar radiation. One way that all this energy is spread to the rest of the planet is by ocean currents. The ocean currents act as big conveyor belts moving this energy not only north and south but also up and down in the ocean.

Causes of Ocean Currents Ocean Currents Video
Convection currents of surface air move the water across the ocean (prevailing winds) The influence of the earth’s rotation from west to east create different current speeds on the east and west coasts of continents The shape of the continents will force the ocean current to travel along its edge The heat capacity of water allows the ocean to store huge amounts of solar energy which causes changes in the local weather and world climate as it is released The amount of salt in the ocean changes as the water evaporates. More salt and less water increases the density of the ocean water so it sinks creating deep water currents

Assignment : To see the effects of ocean currents do the Nike Ocean Currents Activity and then answer the understanding concepts 1-7 on pg 527

13.11 Clouds and Fog Clouds are obvious indicators of weather and weather systems. Learning the characteristics of the various clouds will help you predict what kind of weather is approaching. There are 4 kinds of clouds

Convective – produced when air near the ground absorbs energy from heated surfaces(oceans, lakes, soil), becomes warmer and less dense and rises in the atmosphere. This warm carries water vapor with it and as the air cools it condenses and forms clouds

Frontal – form where the leading edge, or front, of a large moving air mass meets another mass of air at a different temperature. As a warm air mass moves over a cold air mass or a cold air mass moves under a warm air mass the rising warm air cools and condenses into clouds

Orographic – form when air moves up a mountain, expands at the lower pressure and cools. Moisture in this rising air condenses in the colder mountain air and condenses into clouds.

Fog – clouds that form on the ground
Fog – clouds that form on the ground. When warm rising air is not reflected back to earth an area of cold forms condensing the water vapor in the air to form fog.

Classifying Clouds Classification of clouds is from general to specific. The 2 general types are: ·        Cumulus – billowing, round shape which are associated with unstable weather. They usually form as a result of convection or orographic lifting.

Stratus – flattened layered shape are associated stable conditions
Stratus – flattened layered shape are associated stable conditions. They usually form where a cold front meets a warm front

Low level clouds are simply called cumulus or stratus
To further classify clouds they are given names according to their altitude Low level clouds are simply called cumulus or stratus

Medium level clouds are are prefixed with alto

High level clouds are prefixed with cirrus

One more classification is nimbus which indicates a rain holding cloud
World Cloud Animations Orograhic Cloud Photos Cloud Type Website

stratocumulus cumulus nimbostratus altostratus cumulonimbus
Assignment : In your notebook describe in as much detail what each of the cloud types would indicate to you cirrus stratocumulus cumulus nimbostratus altostratus cumulonimbus cirrostratus cirrocumulus stratus Do Understanding Concepts 1- 6 pg 534

13.13 A Global Weather Model You have learned about the atmosphere and prevailing winds, the hydrosphere and ocean currents as well as cloud formations and types of clouds. All these factors are driven by the energy from the Sun. Assignment : Do Understanding Concepts 1-8 pg 537 Do Understanding Concepts 1-3,5,8,10,12,15,18,27 pg 540 Test to Follow Final Project “Gone With The Wind” see next slide

1- Find a reliable partner to work with
Final Project “Gone With The Wind” 1- Find a reliable partner to work with 2-Complete the Tornado and Hurricane Worksheets 3-Choose one of the following web quests and create a Power point presentation.

Hurricane Web Quest Your job in this Webquest is to discover the conditions that create tropical depressions, tropical storms, and hurricanes, and to identify the differences among these storms. You will learn about the component parts of hurricanes and about the source of energy for all tropical storms. You will find out about the scale used to classify hurricanes, and about the most destructive hurricanes ever recorded. You will also discover the relationships between tropical cyclones, typhoons, and hurricanes. Finally, you will answer a set of questions to demonstrate what you have learned about hurricanes

Hurricane Webquest The hurricane season of 2005 has been exceptionally active.  The states of Mississippi, Louisiana, Florida, Alabama, and several more are bracing for one of the largest hurricanes to hit the coast and inland areas in years. As Hurricane Katrina approaches, residents are evacuating and looking for safe places to stay.  South Carolina is prone to hurricanes, but luckily we have not faced a major tropical system this year.  However, the hurricane season is far from over.  How do hurricanes form and why is this year such an active season for hurricanes?  In this web quest, you will find the answers to these questions as well as other questions surrounding the phenomenon of hurricanes.