WEATHER AND CLIMATE

DESCRIBING WEATHER When you describe the conditions outside on a particular day, you are describing the weather. Meteorologists: scientists that study weather. They usually provide the following information when they describe the weather: wind speed, temperature, relative humidity, atmospheric pressure, presence of cloud cover/fog and type/amount of precipitation PREDICTING THE WEATHER

• In some parts of the world the weather stays more or less the same. For example the Sahara desert is usually hot and dry during the day. However, in Canada the weather can change dramatically from one day to the next.

• Because weather does change in parts of the world we often want to know what the weather will be like tomorrow or for the

weekend.

• What causes weather? The movement of air and water as well as the energy of the sun contribute to our weather

• Meteorologists WEATHER STATIONS, WEATHER BALLOONS, AIRCRAFT AND SATELLITES to gather information about weather around the world to forecast the weather for a specific region.

EXTREME WEATHER EVENTS AND CLIMATE From https://www.climatecommunication.org/new/features/extreme-weather/overview/ Recent weather events such as deadly heat waves and devastating floods have sparked popular interest in understanding the role of global warming in driving extreme weather. These events are part of a new pattern of more extreme weather across the globe, shaped in part by human-induced climate change. As the climate has warmed, some types of extreme weather have become more frequent and severe in recent decades, with increases in extreme heat, intense precipitation, and drought. Heat waves are longer and hotter. Heavy rains and flooding are more frequent. In a wide swing between extremes, drought, too, is more intense and more widespread. All weather events are now influenced by climate change because all weather now develops in a different environment than before. While natural variability continues to play a key role in extreme weather, climate change has shifted the odds and changed the natural limits, making certain types of extreme weather more frequent and more intense. The kinds of extreme weather events that would be expected to occur more often in a warming world are indeed increasing. HOW DOES WEATHER RADAR WORK? Radar (Radio Detection and Ranging) was invented during World War II to detect aircraft. Typical radar units consist of a transmitter and a receiver. The transmitter emits pulses of radio waves outward in a circular pattern. For weather, microwaves are used with a wavelength on the order of 3 cm, 5 cm and 10 cm. Precipitation scatters these radio waves, reflecting some energy back to the transmitting point where it is detected by the radar’s receiver. The intensity of this received signal, called the radar echo, indicates the intensity of the precipitation. Measuring the time it takes for the radio wave to leave the radar and return tells us how far away the storm is. The direction the radar is pointing locates the storm. Uniquely, Doppler radar can measure the velocity of precipitation particles (and thus, the wind) in precipitating regions. Doppler radar receiver detects waves with a higher frequency if precipitation particles are moving toward the radar and a lower frequency if particles are moving away. Example 1: A radar receiver detects a pulse 6.00 microseconds after it was transmitted. How far is the storm located from the radar transmitter? WHAT IS CLIMATE?

• Climate is the usual pattern of weather in a region over a LONG PERIOD of time. To determine the climate of a region, climatologists collect weather information over 30 years or more and average the results.

• For example the climate in southern Ontario is warm and humid in the summer, and cold with snow during the winter. • The climate of a region determines the types of plants and animals that live there. (Ex. The Arctic) • What is the difference between weather and climate?

“Climate is what you expect, but weather is what you get.” Robert Heinlein

CLASSIFYING CLIMATE

CLIMATE ZONE: An area where temperature, precipitation and plant communities are similar. (Ex. Polar regions like the Arctic and Antarctic are placed in the same climate zone) Refer to page 322 Figure 2:

• In which climate zone do you live in?_____________________ • Can you find another country containing the same climate zone? _________

ECOREGION: a new climate zone which focuses on the ecology of the region. They are based on landforms, soil, plants, animals and climate. Refer to page 323 Figure 3:

• Which ecoregion do you live in?_____________________________

BIOCLIMATE PROFILE: is a series of graphs that shows temperature and moisture conditions for a certain location. Bioclimate profiles only describe climate, but it displays the location’s projected climate 40 to 80 years into the future.

FACTORS AFFECTING CLIMATE

• The climate in a region is caused by a variety of factors: DISTANCE FROM THE EQUATOR (LATITUDE), PRESENCE OF LARGE BODIES OF WATER, PRESENCE OF OCEAN OR AIR CURRENTS, LAND FORMATIONS, ALTITUDE (HEIGHT ABOVE SEA LEVEL)

THE SUN POWERS EARTH’S CLIMATE SYSTEM

THE BALANCE OF ENERGY ON EARTH Almost all energy on Earth comes from the Sun. The Sun emits a number of different types of radiation (Electromagnetic Spectrum). What happens when radiation from the Sun reaches Earth?

• 30% IS REFLECTED INTO SPACE BY CLOUDS, THE ATMOSPHERE AND THE SURFACE

• 70% IS ABSORBED BY THE EARTH’ SURFACE, CLOUDS AND CERTAIN GASES IN THE ATMOSPHERE From the 70% which is absorbed by the earth’s surface, <1% is used by plants for photosynthesis and the remaining is absorbed by rocks/land and water causing them to heat up. (Fig 3- Pg 326) SOLAR POWER The maximum solar radiation incident on the ground near the equator is around 1120 Watts/m2. Example 1: A solar panel’s dimensions are 650 cm by 1.25 m. The panel has an efficiency of 30%, meaning 30% of the sun’s power is converted into electrical power. If the solar radiation incident on the solar panel is 450 W/m2, calculate the electrical power generated by the solar panel. Example 2: A solar panel has an efficiency of 25%, and generates 600 Watts of electrical power. If the solar radiation incident on the solar panel is 382 W/m2, determine the area of the solar panel. HOW DOES EARTH MAINTAIN BALANCE? If the sun is continuously shining on Earth, why does Earth’s average temperature remain relatively constant?

• THE EARTH ABSORBS ENERGY, BUT EMITS INFRARED ENERGY BACK TO THE ATMOSPHERE • The amount of energy radiated by the Earth is equal to the amount of energy the Earth absorbs from the Sun. This creates a

balance that maintains the global temperature fairly constant. (Fig 5- Pg 328)

LATITUDE AND CLIMATE ZONES Which country would you expect to be warmer, Nigeria or Greenland?

• The climate is warmer at lower latitudes and colder at higher latitudes. • At lower latitudes, near the equator the Sun is shining directly over the Earth’s surface.

• At the higher latitudes, near the North and South poles the Sun is not shining directly overhead.

COMPONENTS OF THE EARTH’S CLIMATE SYSTEM

THE CLIMATE SYSTEM

The Earth’s climate system keeps the global temperature constant and maintains conditions needed for life.

There are four main components to the Earth’s climate system: • ATMOSPHERE • HYDROSPHERE • LITHOSPHERE • LIVING THINGS 1. THE ATMOSPHERE

• The Earth is wrapped in layers of mixed gases, called the atmosphere. • The atmosphere has 5 layers:

• In the troposphere the air we breath is 78% nitrogen, 21% oxygen and 1% other gases including argon, carbon dioxide, helium, hydrogen and ozone.

The function of the atmosphere is to:

• REFLECT, ABSORB and TRANSMITS SOME OF THE SUNS ENERGY • Once the energy reaches the Earth the atmosphere traps much of the energy, warming up the Earth • PROTECTS THE EARTH FROM HARMFUL RADIATION AND METEORS OZONE IN THE STRATOSPHERE

• The Sun causes damage, such as sunburn and skin cancer to living things. • In the stratosphere, ozone absorbs high energy ultraviolet (UV) radiation from the Sun preventing it from reaching the Earth’s

surface. • STRATOSPHERIC OZONE PROTECTS HUMANs AS WELL AS PLANTS AND ANIMALS • The ozone layer however, has become thinner over the Arctic and Antarctic, known as the “ozone hole”, due to human-made

compounds called CFC’s. • CFC’s were used in aerosol spray cans, refrigerators, and air conditioners. • EACH CFC MOLECULE CAN ENTER THE STRATOSPHERE WHERE IT REACTS WITH OZONE, CAUSING IT TO BREAK

DOWN • In 1987, governments around the world signed an agreement to stop the production and use of CFC’s. Since then the ozone has

begun to recover but will take at least 50 more years to return to its original thickness.

OZONE IN THE TROPOSPHERE

• Although ozone in the stratosphere serves a protective role, it has a toxic and corrosive effect in the lower troposphere. • UV RADIATION FROM THE SUN COMBINES WITH THE EXHAUST FROM CARS TO PRODUCE TOXIC CHEMICALS

AND OZONE GAS AT GROUND LEVEL, CALLED PHOTOCHEMICAL SMOG • Photochemical smog is harmful to human health, damages buildings and affects plants and animals.

2. THE HYDROSPHERE

The hydrosphere includes all water on and around Earth.

THE WATER CYCLE • Large bodies of water have an effect on the climate of nearby regions, because water • WATERS WARMS AND COOLS MUCH MORE SLOWLY THAN LAND • Regions near water tend to be cooler in the summer and warmer in the fall/winter. • Regions that are east of a large body of water have more snowfall in the winter. (ex. Lake effect snow) • 2% of all Earth’s water is frozen as either sea ice or land-based ice. • Surfaces covered in ice and snow reflect more radiant energy than surfaces covered in soil and rock.

3. THE LITHOSPHERE

The lithosphere is the Earth’s crust. It includes all the solid rock, soil and minerals on land and extends under the oceans as well.

LAND FORMATIONS &

CLIMATE ZONES • Mountains and other land

formations affect how air moves over an area.

• • This process is called the RAIN

SHADOW EFFECT

ALTITUDE AND CLIMATE ZONES • At high altitudes, atmospheric pressure is LOWER because there is less air above pushing down. • As warm air from the surface of the Earth moves upward,

IT EXPANDS AND COOLS, CREATING A COOLER CLIMATE IN THE MOUNTAINS • The “Alpine Climate” has a strong effect on the ecosystems found at high altitudes.

4. LIVING THINGS

• Through various processes, plants and animals change the relative amount of gases in the atmosphere.

• Through photosynthesis, plants take in carbon dioxide and release oxygen. • Through cellular respiration, animals and other organisms take in oxygen and release

carbon dioxide. • Cows, sheep, termites and some bacteria produce methane gas. • Gases such as carbon dioxide and methane absorb infrared radiation emitted by

Earth.

THE GREENHOUSE EFFECT

• The atmosphere allows much of the radiation from the Sun to pass through. This radiation is absorbed by the Earth’s surface becoming thermal energy.

• THIS CAUSES THE EARTHS SURFACE TO WARM UP AND EMIT INFRARED RADIATION INTO THE

ATMOSPHERE • The gases in the atmosphere trap much of the IR radiation, which warms up the Earth even more. • The trapped energy keeps the Earth’s global temperature (~15oC) much higher than it would be otherwise (~-18oC).

• This energy-trapping process is called the GREENHOUSE EFFECT. This is a natural process that has been happening for

millions of years!

GREENHOUSE GASES

• Most of the atmosphere is made up of NITROGEN and OXYGEN. However, these gases do not absorb radiation. • Greenhouse gases: water vapour, carbon dioxide, methane, ozone, nitrous oxide

ANY GAS IN THE ATMOSPHERE THAT ABSORBS LOW ENERGY INFRARED RADIATION

Carbon Dioxide

• Carbon dioxide is estimated to cause up to a quarter of the natural greenhouse effect on Earth. • Natural sources of carbon dioxide are: CELLULAR RESPIRATION, BURNING ORGANIC MATTER, VOLCANIC

ERUPTIONS • Before industrial age: 280 ppm After industrial age: 385 ppm • The carbon cycle is the movement of carbon through living things, the lithosphere, the atmosphere and the hydrosphere.

Carbon sink: Water Vapour

• Two-thirds of Earth’s natural green house effect is caused by water vapour in the atmosphere. • When water is heated it evaporates and become water vapour, and warmer water evapourates more. • Because water vapour traps energy, the more water vapour there is in the atmosphere, the warmer Earth becomes. • This type of relationship is called a FEEDBACK LOOP. • Water vapour and temperature are related in a POSITIVE FEEDBACK LOOP. • A NEGATIVE FEEDBACK decreases the effects of the interacting parts, and help maintain a system’s balance.

Methane

• A molecule of methane is 23 TIMES more powerful as a greenhouse gas than a molecule of carbon dioxide. • Methane comes from natural sources such as plant decomposition in swamps and animal digestion. • Before industrial age: 0.75 ppm After industrial age: 1.78 ppm

Nitrous Oxide

• Nitrous oxide is 300 TIMES more effective than a molecule of carbon dioxide as a greenhouse gas. However a much smaller concentration of nitrous oxide is present in the atmosphere.

• Nitrous oxide is produced naturally by reactions of bacteria in soil and water. • Before industrial age: 0.288 ppm After industrial age:0.319 ppm

HOW DO GREENHOUSE GASES TRAP RADIATION?

• Nitrogen and oxygen gas each consist of two identical atoms. This means that these molecules can only vibrate back and forth, which limits the type of energy that these molecules can absorb. They cannot absorb IR radiation.

• Water, carbon dioxide, methane and nitrous oxide all have three or more atoms, and have different types of atoms. The atoms in

these molecules can vibrate and wiggle in many ways, and can absorb different types of energy.

• Therefore, when IR radiation reaches these molecules, they trap the IR energy and re-radiate it back out in every direction.

MEASURING CARBON DIOXIDE CONCENTRATIONS: Historically and Present Day (Mauna Loa) Historically (record of past hundred thousand years) Ice cores provide a direct archive of past atmospheric gases. In Greenland and Antarctica, large ice sheets provide ideal areas to drill ice cores. When the ice forms (originally as fallen snow), air is trapped in the ice. Ice cores can vary in length 100 to 200 metres deep or up to 3000 metres deep. The air bubbles are extracted by melting, crushing or grating the ice in a vacuum. Ice cores have been used to estimate ___________ ___________ concentration in ppm _______ ______ ____________and estimate the earth’s average temperature. Daily Measurements Air is slowly pumped through a small cylindrical cell with flat windows on both ends. Infrared radiation is transmitted through one window, through the cell, through the second window, and is measured by a detector that is sensitive to infrared radiation. In the atmosphere, carbon dioxide absorbs infrared radiation. In the cell, carbon dioxide absorbs infrared light. More carbon dioxide in the cell causes more absorption, leaving less light to hit the detector. Hence, a smaller signal is measured. The signal measured by the detector is converted into a carbon dioxide concentration Diagram:

ENERGY TRANSFER: AIR AND OCEAN CIRCULATION

• The atmosphere and the hydrosphere are able to absorb and store thermal energy, so they act as heat sinks. • The ocean is particularly important heat sink because

ENERGY TRANSFER IN THE ATMOSPHERE

- occurs due to the differences in intensity of solar radiation ENERGY TRANSFER IN THE OCEANS

• Water at the poles is colder and saltier then water at the equator. This makes the water at the poles MORE DENSE and therefore SINKS to the ocean floor.

• The warmer surface water from the equator then flows to the POLES to take its place. • This process is called THERMOHALINE CIRCULATION of the oceans; the continuous flow of water around the world’s

oceans driven by differences in TEMPERATURE and SALINITY. • Ocean currents around the globe act like enormous “CONVEYOR BELTS” slowly moving water and thermal energy from the

equator to the poles. • Ocean currents can also be caused by winds, which is actually the main cause of the Gulf Stream; which transports warm water

from the tropics up the east coast of North America and across to Europe. EFFECT OF OCEAN CURRENTS ON CLIMATE

• Warm ocean currents heat the air above them. WHEN THE WARM MOIST AIR REACHES LAND, IT WARMS THE LAND AND PRODUCES RAIN

• Ex. Northwest coast of Europe has a warmer, damper climate than other places at that latitude because of the warm Gulf stream.

• Cool ocean currents cool the air above them WHEN THE COLD DRY AIR REACHES LAND, IT COOLS THE LAND AND CREATES DESERTS Ex. California and parts of Mexico are cooler and drier because of a cold ocean current along their west coast.

LONG-TERM AND SHORT-TERM CHANGES IN CLIMATE

Read textbook pages 348-352 to answer the following questions on page 353 1, 2, 3 abc, 4, 5, 8. Also define the following terms: Iceage, Plate tectonics, Continental drift, Interglacial period, El Nino Scientists have discovered that Earth’s climate goes through a variety of natural changes. Changes in climate are triggered by changes in the Earth’s __________________________.

FEEDBACK LOOPS AND CLIMATE

Small changes, such as a decrease in snow cover, can have a very large effect on the Earth’s climate. This is because small changes can be enhanced by feedback loops.

• A positive feedback loop, the effect increases the original cause. • A negative feedback loop, the effect decreases the original cause.

WATER VAPOUR FEEDBACK LOOP Positive Feedback: As water warms up it evaporates into the atmosphere. This causes the climate to warm up even more because water is a greenhouse gas and traps infrared radiation emitted by Earth. This feedback loop becomes more complex when you consider clouds. More water vapour usually means more clouds. If the clouds are low in the atmosphere then they trap heat near the surface. (Ex. Cloudy nights are warmer then clear nights) Negative feedback: If clouds form at high altitudes then they reflect the Sun’s radiation back out to space.

THE ALBEDO EFFECT

• Different surfaces reflect different amounts of the Sun’s radiation. The percentage of radiation reflected by a surface is called

it’s albedo. Ice and snow have a high albedo compared to grass and trees. The Earth’s average albedo is between 0.3 and 0.4.

(30%-40% reflection)

• Albedo Effect: the positive feedback loop in which an increase in Earth’s temperature causes ice to melt, so more radiation is absorbed by Earth’s surface, leading to further increases in temperature.

Read textbook pages 355 to 357 and answer question 1, 2, 3, 5 on page 357