Science 10 Chapter 10.3_keyed

Chapter 10 - Solar Energy and Climates (pages 362 - 399 in your text)

Chapter 10.3 – Distributing the Heat (pages 388 – 396 in your text)

Every year, Calgary hosts a winter carnival where you can see really “cool” ice sculptures. During Calgary’s winter, ice sculptures are usually able to remain frozen. Meanwhile, only approximately 1000 km away, Vancouver’s winters are mild—too mild to maintain ice sculptures over weeks at a time.

Vancouver’s winters are mild, especially compared to the prairie cities, due to thermal energy carried by a warm ocean currents flowing past the west coast. Ocean currents carry much of the thermal energy transferred by the hydrosphere. These transfers of thermal energy have a profound effect on climate around the globe.

How Oceans Distribute Heat

Water has a low albedo and absorbs more than 90% of the solar energy striking it. Because of water’s high specific heat capacity and large heats of vaporization and fusion, it takes a lot of energy to change its temperature or phase. The energy absorbed by water is distributed throughout great water depths due to waves, turbulence and ocean currents.

The Gulf Stream is a large surface current that starts in the Caribbean and follows the coastline of the United States and Canada. It ends up off the European coast, where it is called the North Atlantic Drift. This current helps to moderate the climates of Western Europe.

El Niño and La Niña

El Niño is a disruption of the ocean-atmosphere system in the tropical Pacific that typically occurs every three to seven years. During an El Niño year, the wind direction over the South Pacific reverses and the winds flow eastward. The wind reversal causes an increase in the sea-surface temperature, causing heavy rains in South America and droughts in Asia and Australia. It is not known why the winds reverse directions. El Niño can affect weather patterns across 25% of the globe.La Niña is the opposite of El Niño. La Niña is characterized by an increase in the strength of the normal patterns of westward moving winds. La Niña produces wetter than normal conditions in Australia and Asia. North America becomes warmer and drier than in non- La Niña years.Here is a rule that is not always exactly true, but still is useful to compare the impacts of El Niño and his contrary sister. Where El Niño is warm, La Niña is cool. Where El Niño is wet, La Niña is dry. While El Niño conditions and their seasonal impacts look very different from normal, La Niña conditions often bring winters that are typical — only

Science 10 Chapter 10.3_keyed

more so. There's something else to keep in mind: El Niño and La Niña tend to make seasonal conditions one way or another, but every El Niño and La Niña is different.

What to do: Answer the questions below.Question 1. In the northern hemisphere, ocean currents that flow north tend to be warm currents and those that flow south tend to be cold currents. Give a reason for this.In the northern hemisphere, ocean currents that flow north tend to be warm currents because they are coming from the warmer regions close to the equator. Ocean currents that flow south tend to be cold currents because they are coming from the cooler, polar regions.

Question 2. In which hemisphere do ocean currents flow clockwise? In which hemisphere do they flow counterclockwise?Ocean currents flow clockwise in the northern hemisphere and counterclockwise in the southern hemisphere.

Question 3. Name the regularly occurring disruption of ocean currents in the tropical Pacific that is linked to severe weather and climate events around the globe.This disruption of the ocean currents is called El Niño.

Patterns of Wind Movement

Living in Alberta, you probably notice that wind most often comes from the west. That is because Alberta is in the temperate zone where west-to-east winds blow. These winds, called prevailing westerlies, contribute to global wind patterns.

animation of global wind patterns

At the equator, warm air rises and loses its moisture. At 30◦, dry air descends; therefore, deserts occur at 30◦ latitude around the world.

Because the Earth is rotating on its axis, the trade winds move from the northwest to the west in the Northern hemisphere, and from southeast to the west in the Southern hemisphere. This is called the Coriolis effect.

The westerlies move from the west, towards the east.

Differences in atmospheric pressure in neighbouring regions on Earth’s surface lead to wind.An area of low pressure occurs as warm air expands, becomes less dense, and rises from the surface. High pressure occurs as cold air contracts, becomes denser, and descends to the surface. This movement of air forms convection currents that circulate and distribute heat around the world.

Science 10 Chapter 10.3_keyed

The Earth is constantly rotating and the atmosphere rotates with it at the same speed. Convection currents or any moving object tend to veer sideways from their original course due to Earth’s rotating eastward on its axis. This tendency is called the Coriolis effect.

Jet Streams

Jet streams are currents of extremely fast-moving air about 10-15 km above Earth’s surface. Jet streams form at the boundaries of cold and warm air. Jet streams are usually larger in the winter when the temperature difference between cold and warm air masses is greatest. Intense winds within jet streams influence precipitation and thunderstorms.

What to do: Answer the questions below.Question 4. In which direction does air move with regards to pressure areas?Air moves from a high-pressure area to a low-pressure area.

Question 5. Why does an area of high pressure form where the air is cold?When air cools, it contracts and becomes more dense. A column of more dense air exerts morepressure and, thus, forms an area of high pressure.

Question 6. Earth’s rotation deflects airflow from a direct north-south direction. What isthis deflection called? The deflection of airflow due to Earth’s rotation is called the Coriolis effect.

Oceans and Mountains Influence ClimateSea and land breezes form as a result of the vastly different specific heat capacities of water and land. Water heats and cools at a slower rate than land. This results in a temperature differential between the two bodies.Sea Breeze (occurs during the day)A – Sun’s rays warm the land faster than they warm the waterB – Warm air is less dense; warm air rises.C – Air over the water is cooler; cool air is more dense and sinks.D – Cool air flows towards land to replace the warm air that has risen

Land Breeze (occurs at night)A – The sea loses heat more slowly than the land. The air over the sea is warmer.B – Warm air over the sea rises.C – Air over land is cooler; cool air is more dense and sinks.

Science 10 Chapter 10.3_keyed

D – Cool air flows towards the sea to replace the warm air that has risen.

What to Do: Answer each question in the space provided. 1. Explain why different surfaces absorb different amounts of solar energy.The phenomenon is called albedo. Dark surfaces absorb solar energy, while light surfaces reflect

solar energy.

2. Match the description in column A with the correct term in column B. Write the term in the line beside the description.A(a) relatively fast uniform winds that are found in the upper atmosphere in a

narrow band jet stream(b) phenomenon that causes moving air masses to be deflected to the right

in the Northern Hemisphere and to the left in the Southern Hemisphere Coriolis Effect

(c) movement of a gas or a liquid because of heating convection(d) name given to the occasional development of warm ocean surface

waters along the coast of Ecuador and Peru El Nino(e) condition that develops when warm air rises and becomes less dense low pressure(f) condition that develops when cold air contracts and becomes more

dense high pressure(g) warm Atlantic current that splits into two as it reaches the British Isles

North Atlantic Drift(i) breezes that occur during the day due to differential heating between

land and water sea breeze(j) breezes that occur during the night due to differential cooling between

land and water land breeze(k) measure of the how much radiation a substance or an object reflects

albedo(l) warm ocean current that originates in and around the Caribbean and

flows across the North Atlantic to northwest Europe Gulf Stream

3. Sketch a diagram of either a sea breeze or a land breeze. Include the following labels with your diagram: - “sea breeze” or “land breeze” - “daytime” or “nighttime” - “hot” - “cool” - “warmer air rising” - “cooler air sinking” - arrows showing direction of breeze.

Balbedo

convection

Coriolis effect

El Niño

Gulf Stream

high pressure

jet stream

land breeze

low pressure

North Atlantic Drift

sea breeze