Weather and Climate

Question 1

Define “Weather”.

Answer 1

The condition of the atmosphere at a particular place and time.

Question 2

Define “Climate”.

Answer 2

The average condition of the atmosphere of a specific place over a long period of time, usually over 30 years.

Question 3

Explain how latitude affects temperature.

Answer 3

Latitude is the distance of any point on the earth measured north or south from the equator.

At lower latitudes, the sun’s rays hit the earth’s surface at a higher angle of incidence, causing the heat to be concentrated on a small area, resulting in higher temperatures.

At higher latitudes, the sun’s rays hit the earth’s surface at a lower angle of incidence, causing the heat to be spread out over a larger area, resulting in lower temperatures.

Question 4

Explain why places at higher altitudes have lower temperatures.

Answer 4

The atmosphere is mostly heated by the earth’s surface. The higher up you are, the further you are from the surface of the earth that is heated by the sun. Therefore, temperature decreases with increasing altitude

Longwave radiation that is emitted by the earth is absorbed by greenhouse gases such as Co2 in the atmosphere, trapping the heat and warming the earth.

Air is less dense at higher altitudes. Dense air is able to absorb more heat from longwave radiation from the earths surface , resulting in higher temperatures. Less dense air has less ability to absorb heat, causing these lower temperatures.

Question 5

Explain the maritime effect.

Answer 5

Maritime effect is the effect that large ocean bodies have on the climate of coastal areas, resulting in a lower annual temperature range.

During summer, the air over the sea is cooler than the air over the land, as the land heats up faster than the sea. The cooler air over the sea helps to lower the temperature of the area, resulting in cooler summers.

During winter, the air over the sea is higher than the air over the land, as the land cools down faster than the sea. The warmer air over the sea helps increase the temperature of the area, resulting in warmer winters.

Question 6

Explain why inland areas have a higher annual temperature range.

Answer 6

Inland areas have a higher annual temperature range due to the continental effect.

During summer, the land heats up quickly, while during winter, the land cools down quickly. As a result, inland areas experience hotter summers and colder winters, leading to a higher annual temperature range.

Question 7

Explain why there is a larger daily temperature range in the desert.

Answer 7

Deserts lack cloud cover.

In the day, all of the sun’s energy is thus able to reach the earth’s surface, heating it up quickly and causing the temperature to increase.

At night, most of the heat radiated from the earth’s surface escapes into the atmosphere, causing temperatures to drop.

Question 8

Explain why places with cloud cover have a lower daily temperature range.

Answer 8

In the day, the clouds reflect a large portion of the sun’s energy back to space, keeping the earth’s surface cool. At the same time, the clouds absorbs some of the heat radiated from the earth’s surface, lowering the temperature.

At night, the clouds absorbs some of the heat radiated from the earth’s surface, preventing them from escaping into space, keeping the earth warmer.

Question 9

Explain the factors affecting relative humidity.

Answer 9

1. Temperature.

Higher temperatures can hold more water vapour. Given the same amount of water vapour, places with higher temperature will therefore have a lower relative humidity compared to a place with lower temperature.

Higher temperatures result in more evaporation -> more water vapour -> higher relative humidity.

2. Amount of water vapour

Coastal areas or places near water bodies have higher chances of evaporation -> more water vapour -> higher relative humidity.

More trees -> more transpiration -> higher relative humidity.

Question 10

Explain the formation of relief rain.

Answer 10

1. Warm, moist air from the sea is forced to rise due to the mountains.
2. Air cools as it rises. When dew point temperature is reached, condensation occurs and cloud form. When the water droplets are large and heavy enough, rain falls on the windward side.
3. By the time air moves to leeward side, the air is dry and there is no rain fall.

Question 11

Explain the formation of convectional rain.

Answer 11

1. Convectional rain occurs when the earth’s surface is heated intensely. As the sun’s energy heats up the earth’s surface, the warm surface heats the air around it.
2. The air becomes unstable, causing it to expand and rise.
3. As the air rises, its temperature begins to drop. When the rising air cools to dew point temperature, condensation occurs and clouds are formed.
4. When the water droplets in the clouds become large and heavy enough, they fall to the ground as rain.

Question 12

Define ‘air pressure’.

Answer 12

Air pressure is the force on an unit area of the earth’s surface by the weight of a column of air above it.

Question 13

Explain how wind is formed.

Answer 13

When there is a difference in temperature and thus a difference in air pressure, the air moves from an area of high pressure to an area of low pressure, forming wind.

Question 14

Explain the formation of land breeze.

Answer 14

1. At night, the land cools down faster than the sea. This results in the land having a lower temperature than the sea.
2. The land thus has a higher air pressure compared to the sea.
3. As winds blow from an area of high pressure to low pressure, the winds blow from the land to the sea, forming land breeze.

Question 15

Explain how the sea breeze helps moderate temperatures during the day.

Answer 15

1. In the day, the land heats up faster than the sea. This results in the land having a higher temperature than the sea.
2. The land thus has a lower air pressure compared to the sea.
3. As winds blow from an area of high pressure to low pressure, the winds blow from the sea to the land, forming sea breeze and lowering the temperature of the coastal area.

Question 16

Explain the Coriolis effect.

Answer 16

The coriolis effect is the force produced by the earth’s rotation.

Winds deflect right in the northern hemisphere and left in the southern hemisphere.

The coriolis effect is strongest at the poles but is not felt at the equator.

Question 17

Explain the formation of the northeast monsoon.

Answer 17

1. Between December and February, the Northern hemisphere is experiencing winter while the Southern hemisphere is experiencing summer.
2. The Northern hemisphere thus has a higher air pressure compared to the Southern hemisphere.
3. As winds blow from an area of high pressure to low pressure, the winds blow from the north down towards the Southern hemisphere.
4. Due to the coriolis effect, the winds are deflected right in the northern hemisphere to form the northeast monsoon.
5. As the winds pass the equator, they are now deflected left due to the coriolis effect.
6. The winds pick up moisture from the Indian Ocean, bringing heavy rain to Australia as the northwest monsoon.

Question 18

Explain the formation of the southwest monsoon.

Answer 18

1. Between June and September, the Northern hemisphere is experiencing summer while the Southern hemisphere is experiencing winter.
2. The Northern hemisphere thus has a lower air pressure compared to the Southern hemisphere.
3. As winds blow from an area of high pressure to low pressure, the winds blow from the south up towards the Northern hemisphere.
4. Due to the coriolis effect, the winds are deflected left in the southern hemisphere to form the southeast monsoon.
5. As the winds pass the equator, they are now deflected right due to the coriolis effect.
6. The winds pick up moisture from the Indian Ocean, bringing heavy rain to the Indian sub-continent as the southwest monsoon.

Question 19

Describe the characteristics of equatorial climate.

Answer 19

1. Located between 10 degrees north and south of the equator.
2. High mean annual temperatures of about 27 degrees.
3. Small annual temperature range of around 2 degrees.
4. High relative humidity of over 80% throughout the year.
5. High total annual rainfall of more than 2000mm.
6. Constant rainfall throughout the year.

Question 20

Why do tropical areas have high mean annual temperatures and rainfall?

Answer 20

1. Located near the equator -> concentration of heat from the sun -> higher mean annual temperatures.
2. High temperatures -> high evaporation rates -> increased cloud formation -> more rain.

Question 21

Describe the characteristics of the monsoon climate.

Answer 21

1. Located between 5 -25 degrees north and south of the equator.
2. High mean annual temperatures of about 28 degrees.
3. Small annual temperature range of around 3 - 4 degrees.
4. High total annual rainfall of around 2000mm.
5. Distinct wet and dry season depending on the monsoon winds.

Question 22

Describe the characteristics of the cool temperate climate.

Answer 22

1. Located at coastal areas between 40 - 60 degrees north and south of the equator.
2. Low to moderate mean annual temperature ranging from -3 to 18 degrees.
3. Large annual temperature range of around 21 degrees.
4. Low total annual rainfall of 300 - 900mm.
5. No distinct wet and dry season.
6. Experiences the four seasons, spring, summer, autumn, winter.

Question 23

Define ‘climate change’.

Answer 23

Variations in the global climate or climatic patterns in the long term

Question 24

Explain the greenhouse effect.

Answer 24

A natural process by which greenhouse gases trap heat in the atmosphere.

Question 25

Explain the enhanced greenhouse effect.

Answer 25

An increase in greenhouse gases trapping heat in the atmosphere as a result of human activities.

Question 26

Explain how variations in solar output affect climatic changes.

Answer 26

1. The sun emits varying amounts of solar radiation due to changes in its magnetic field, affecting the earth’s climate.
2. During periods of intense solar magnetic activity, the number of sunspots increase, resulting in higher solar radiation, and thus higher temperatures globally.
3. The number of sunspots rise and falls with an approximate 11 year cycle and the earth’s temperature rises and falls correspondingly.

Question 27

Explain how volcanic eruptions can have a cooling influence on the earth’s climate.

Answer 27

1. When a volcano erupts, large volumes of carbon dioxide, water vapour, sulfur dioxide, dust and ash are released.
2. The sulfur dioxide reacts with water to form sulfur-based particles in the atmosphere.
3. Together with the ash and dust, they reflect solar energy back into space, causing a cooling influence on regional and global temperatures.

Question 28

Explain how deforestation has resulted in the enhanced greenhouse effect.

Answer 28

1. Trees are green lungs of the earth, taking in carbon dioxide and giving out oxygen. With deforestation, there is less trees to take in carbon dioxide, leading to more carbon dioxide in the atmosphere, resulting in the enhanced greenhouse effect.
2. When trees are cut down, the soil is exposed, allowing carbon oxidation of the soil to take place, resulting in more carbon dioxide in the atmosphere, resulting in the enhanced greenhouse effect.

Question 29

Explain how clouds form.

Answer 29

1. Evaporation from water bodies and transpiration from trees , lead to water vapour in the atmosphere.
   2, When the water vapour cools at dew point temperature, condensation takes place to form water droplets.
2. The water droplets merge and become larger to form clouds.

Question 30

Explain how industries have resulted in the enhanced greenhouse effect.

Answer 30

1. Use of fossil fuel that gives off carbon dioxide.
2. Greenhouse gases released during the manufacturing process.

Question 31

Explain how urbanisation has resulted in the enhanced greenhouse effect.

Answer 31

1. Vehicular use and household appliances give off greenhouse gases, contributing to the enhanced greenhouse effect.
2. Burning of fossil fuels to provide energy for household activities and transport.

Question 32

Explain how agriculture has resulted in the enhanced greenhouse effect.

Answer 32

1. Burning of fossil fuels to provide energy to operate machines for farming.
2. Methane produced by cattle farming.

Question 33

Explain how climate change has led to sea levels rising.

Answer 33

1. Increased global temperature -> ice caps melt -> increase in sea levels -> threaten low lying areas and islands.
2. Increased global temperature -> water bodies expand -> increase in volume causing sea levels to rise -> threaten low lying areas and islands.

Question 34

Explain how climate change has led to more frequent extreme weather events.

Answer 34

1. Increased latent heat as temperatures increase -> more heat to power tropical cyclones -> more frequent and extreme weather events.
2. Increased global temperatures -> increased rate of evaporation -> more clouds are formed -> increased rainfall -> more floods if countries cannot cope with the increased rain.
3. Increased global temperatures -> water bodies dry up -> more droughts.

Question 35

Explain how climate change has led to the spread of some infectious insect-borne diseases.

Answer 35

Increased global temperatures -> more conducive environment for mosquitos to breed -> more insect-borne diseases.

Question 36

Explain how climate change has led to the lengthening of growing season in certain regions.

Answer 36

Increased global temperatures -> more optimal temperature for growing of crops -> crops have a longer season to grow -> increase food supply.

However, crops that require colder climates to grow will see a decrease in production.

Question 37

Explain how the Kyoto Protocol has helped in managing climate change.

Answer 37

Clear targets are set for each country to reduce greenhouse gas emissions and countries are accountable for meeting their targets.

Question 38

Describe the successes and limitations of the Kyoto Protocol in reducing greenhouse gas emissions.

Answer 38

Success: Between 1990 and 2012, the original Kyoto Protocol parties reduced their CO2 emissions by 12.5%.

Limitation: Even though most Kyoto Protocol signatories succeeded in cutting emissions, worldwide atmospheric CO2 levels have soared, now up 35 percent since 1997.

Question 39

Explain how Singapore aims to reduce greenhouse gas emissions through the Singapore Green Plan 2012

Answer 39

Launched in 2002 with the goal to reduce greenhouse gas emissions and reduce energy consumption by using natural gas as an energy source. it aims to generate 60% of Singapore’s needs using natural gas by 2012.

Question 40

Discuss the effectiveness of the Singapore Green Plan 2012 in reducing greenhouse gas emissions

Answer 40

Success: As early as 2010, about 79% of Singapore’s electricity was generated by natural gas (exceeded target)

Limitation: High maintenance costs due to pipelines being laid underground and have to be checked regularly for leakage.

Question 41

Explain how the Green Mark Scheme helps in combatting global warming.

Answer 41

Launched in 2005 to encourage construction of ‘green’ buildings which are more energy efficient and environmentally friendly, and thus less greenhouse gas emissions.

Question 42

Discuss the effectiveness of the Singapore Green Mark Scheme in combatting global warming.

Answer 42

Success: Existing green buildings (such as Plaza by the Park, Standard Chartered @ Changi and the National Library Building) have reported energy savings of 15% - 35%

Limitations: Construction companies and developers tend to be conservative about building green buildings. Green buildings cost more to build.

Question 43

Explain how the Plant-A-Tree programme helps in minimising global warming.

Answer 43

Started in 1971 with the aim to maintain Singapore’s status as a Garden City by planting more trees and plants.

With more trees 🡪 take in more carbon dioxide, gives out more oxygen 🡪 less CO2 in the atmosphere 🡪 less trapping of heat 🡪 manage global warming.

Question 44

Discuss the effectiveness of the Plant-A-Tree programme in managing global warming.

Answer 44

Success: 60,000 trees planted yearly by National Parks Board (NParks).

Limitations: Trees take 20-30 years to fully grow and are unable to immediately reduce CO2 levels .