Unit 2 (Revision Guide)

Question 1

What is sensible heat transfer?

Answer 1

Sensible heat transfer is the energy required to change the temperature of a substance with no phase change. It occurs when incoming short-wave solar radiation is absorbed by the land surface and then re-radiated as long-wave Earth radiation, heating the air above.

In simple terms: It’s when something gets warmer or cooler without changing state, like the ground heating the air above it.

Question 2

What is latent heat transfer?

Answer 2

Latent heat transfer is the energy absorbed or released during a phase change, such as when water changes to water vapour by evaporation or vice versa by condensation. This transfer helps regulate temperature and can cool the atmosphere during evaporation or warm it during condensation.

In simple terms: It’s the heat used or released when water changes between liquid, gas, and solid states.

Question 3

What is solar radiation?

Answer 3

Solar radiation is incoming shortwave radiation from the Sun that reaches the Earth’s atmosphere. It includes visible light, ultraviolet, and infrared radiation, and is a primary source of energy driving the Earth’s climate and weather systems.

In simple terms: It’s the sunlight and energy that come directly from the Sun.

Question 4

What is terrestrial radiation?

Answer 4

Terrestrial radiation is long-wave radiation emitted by the Earth’s surface after absorbing solar radiation. Most of this energy is absorbed by greenhouse gases in the atmosphere, helping to warm the planet, while a small portion is lost to space.

In simple terms: It’s the heat the Earth gives off after absorbing sunlight.

Question 5

How is solar radiation reflected?

Answer 5

Solar radiation is reflected by clouds, the Earth’s surface, and atmospheric particles. The amount reflected depends on the surface’s albedo, with snow and ice reflecting more, while darker surfaces reflect less. Clouds can reflect 30–90% of incoming radiation depending on their type and thickness.

In simple terms: Some sunlight bounces off clouds, ice, and the ground back into space.

Question 6

What are two methods by which heat received from solar radiation at the Equator is transferred towards the poles?

Answer 6

Detailed Answer: Heat is transferred by sensible heat transfers through winds (80%) and by ocean currents (20%) moving warm water towards the poles.

Simple Terms: Heat moves to the poles mostly by winds and some by ocean currents.

Question 7

Why is the solar radiation received at the Equator lower than that received at the tropics?

Answer 7

Detailed Answer: The solar radiation is lower at the Equator due to large cloud masses that absorb and reflect more solar energy compared to the clearer skies at the tropics.

Simple Terms: There are more clouds at the Equator that block the sunlight.

Question 8

How do daytime and nighttime patterns of wind circulation occur?

Answer 8

Detailed Answer: During the day, land heats up faster than the sea, causing air to rise and create low pressure, drawing in cooler air from the sea (sea breeze). At night, land cools faster, causing high pressure and wind to move from land to sea (land breeze).

Simple Terms: Wind blows from the sea to land during the day and from land to sea at night.

Question 9

What are two effects that land and sea breezes may have upon local weather?

Answer 9

Detailed Answer: Land and sea breezes can influence local temperatures by cooling or warming coastal areas and affect humidity by transporting moist or dry air.

Simple Terms: They can change the temperature and humidity near the coast.

Question 10

How do differences in energy exchanges between day and night occur?

Answer 10

Detailed Answer: During the day, land heats up rapidly, causing warm air to rise and cooler air to replace it. At night, land loses heat quickly, causing cooler air to sink and replace warmer air over the sea. These exchanges are due to the different specific heat capacities of land and sea.

Simple Terms: Land heats up quickly during the day and cools quickly at night.

Question 11

How can warm and cool ocean currents affect temperatures on land?

Answer 11

Detailed Answer: Warm ocean currents, such as the Gulf Stream, transfer heat to coastal regions, making them warmer. Cool currents, like the California Current, lower temperatures of nearby coastal areas by absorbing heat from the atmosphere.

Simple Terms: Warm currents make coasts warmer, and cool currents make them cooler.

Question 12

How can the global distribution of temperatures be influenced by areas of land and sea?

Answer 12

Detailed Answer: Land heats up and cools down faster than the sea due to lower specific heat capacity. This leads to greater temperature variations over land and influences the position and movement of isotherms globally.

Simple Terms: Land changes temperature faster than the sea, causing bigger temperature differences.

Question 13

What is evaporation?

Answer 13

Evaporation is the process by which a liquid is changed into a gas by molecular transfer. This typically occurs when water is heated by the sun, causing water molecules to escape into the air as water vapor.

In simple terms: It’s when water turns into gas because of heat.

Question 14

What is condensation?

Answer 14

Condensation is the process by which water vapor in the air cools and changes into liquid water or ice. It usually requires condensation nuclei, such as dust particles, to form water droplets or ice crystals, leading to cloud formation.

In simple terms: It’s when gas turns back into water or ice.

Question 15

What conditions help the process of evaporation?

Answer 15

Evaporation is enhanced by high air temperature, strong wind speed, and the presence of a large water source, such as a sea or lake. High solar radiation also speeds up the process by providing energy to break molecular bonds.

In simple terms: Heat, wind, and lots of water make evaporation happen faster.

Question 16

What is sublimation?

Answer 16

Sublimation is the process by which water vapor changes directly into ice crystals without becoming liquid, or ice turns directly into vapor. It occurs in very cold conditions, often at high altitudes, and is seen in the formation of snow and frost.

In simple terms: It’s when ice turns into gas or gas turns into ice without becoming water first.

Question 17

What is relative humidity?

Answer 17

Relative humidity is the amount of moisture in the air compared to the maximum amount the air can hold at a given temperature. It is expressed as a percentage; 100% relative humidity means the air is fully saturated.

In simple terms: It shows how full the air is with water.

Question 18

How are clouds and rain formed by the uplift of air?

Answer 18

When air is lifted, it expands and cools. As the temperature drops, the air reaches its dew point, causing water vapor to condense into water droplets or ice crystals, forming clouds. Continued condensation can lead to the growth of droplets, resulting in precipitation.

In simple terms: Air rises, cools, and turns into clouds and rain.

Question 19

What is conventional uplift?

Answer 19

Conventional uplift occurs when the ground heats the air above it, causing the air to rise. As the air rises, it cools and condenses, forming clouds. If enough moisture is present, this process can result in precipitation, such as rain or thunderstorms.

In simple terms: Warm ground makes air go up, cool down, and form clouds and rain.

Question 20

What is orographic uplift?

Answer 20

Orographic uplift occurs when moist air is forced to rise over a mountain range. As the air ascends, it cools and condenses to form clouds and precipitation on the windward side, while the leeward side often remains dry, creating a rain shadow effect.

In simple terms: Mountains push air up, making clouds and rain on one side.

Question 21

How are clouds and rainfall produced?

Answer 21

Clouds and rainfall are produced when warm, moist air rises and cools to its dew point. This cooling causes water vapor to condense into tiny droplets that form clouds. When these droplets combine and grow large enough, they fall to the ground as precipitation.

In simple terms: Warm air rises, cools, forms clouds, and then rain falls.

Question 22

How are clouds and fog formed?

Answer 22

Clouds form when air rises, cools, and reaches its dew point, causing water vapor to condense into droplets at higher altitudes. Fog forms similarly but near the ground, often when warm, moist air moves over a cooler surface or when radiation cooling occurs at night.

In simple terms: Clouds form high up; fog forms close to the ground when air cools.

Question 23

What conditions lead to the formation of dew?

Answer 23

Dew forms during clear, calm nights when the ground cools rapidly by radiation, causing the air near the surface to cool to its dew point. Water vapor then condenses directly onto cool surfaces, such as grass and leaves.

In simple terms: Dew forms at night when the ground cools and water sticks to things.

Question 24

What is the dew point?

Answer 24

The dew point is the temperature at which air becomes fully saturated with water vapor, causing the vapor to condense into liquid water or ice. It is a critical factor in cloud, fog, and dew formation.

In simple terms: It’s the temperature when air is full of water and makes dew or fog.

Question 25

How is snow formed?

Answer 25

Snow is formed when water vapor in the atmosphere sublimates directly into ice crystals without becoming liquid. This typically occurs in clouds when temperatures are below freezing, leading to the growth of ice crystals that fall as snowflakes. In simple terms: Snow forms when water vapor turns straight into ice crystals in cold clouds.

Question 26

What are the differences between snow and hail?

Answer 26

Snow forms when water vapor sublimates directly into ice crystals under freezing conditions. Hail forms in strong updrafts within cumulonimbus clouds, where raindrops are repeatedly lifted above the freezing level, accumulating layers of ice before falling to the ground. In simple terms: Snow is soft ice crystals; hail is hard balls of ice formed in storm clouds.

Question 27

How can an increase in greenhouse gases cause changes to both temperature and precipitation?

Answer 27

An increase in greenhouse gases traps more heat in the Earth's atmosphere, raising global temperatures. This warming enhances evaporation rates, which increases moisture in the atmosphere, leading to altered precipitation patterns and more extreme weather events. In simple terms: More greenhouse gases trap more heat, making Earth warmer and causing more evaporation and changing rain patterns.

Question 28

What are the possible causes of present-day global warming?

Answer 28

Present-day global warming is primarily caused by human activities such as deforestation, burning fossil fuels (coal, oil, natural gas), and industrialization. Additional factors include methane emissions from livestock and wetlands, melting permafrost releasing stored methane, and chlorofluorocarbons (CFCs) used in cooling systems and aerosols, which trap heat effectively. In simple terms: Burning fuels, cutting trees, and gases from farms and factories trap heat and warm the Earth.

Question 29

How have human activities contributed to global warming, and why may the consequences of sea-level rise be more severe in some areas?

Answer 29

Human activities, like deforestation and the burning of fossil fuels, increase greenhouse gases, leading to global warming and polar ice melting. The resulting sea-level rise poses a greater threat to low-lying coastal areas and developing nations with limited resources for coastal defenses, making them more vulnerable to flooding and erosion. In simple terms: People burn fuels and cut trees, causing ice to melt and sea levels to rise, which is worse for low-lying areas.

Question 30

What is meant by the term urban heat island (UHI)?

Answer 30

The urban heat island (UHI) effect occurs when urban areas become significantly warmer than surrounding rural areas. This is due to the absorption and re-radiation of heat by buildings, roads, and other infrastructure, along with reduced vegetation and the presence of heat-retaining materials like concrete and asphalt. The UHI effect is more pronounced at night and can increase energy demands for cooling and exacerbate air pollution. In simple terms: Cities are hotter than nearby countryside because roads and buildings trap heat.

Question 31

What is one effect that atmospheric pollution may have upon urban climates?

Answer 31

Atmospheric pollution in urban areas can lead to the formation of smog, which traps heat and raises temperatures. Pollutants like carbon dioxide, nitrogen oxides, and particulates enhance the greenhouse effect locally, reducing the escape of heat from the urban atmosphere and worsening the urban heat island effect. In simple terms: Pollution makes cities hotter and causes smog.

Question 32

Why is air pollution higher in urban areas?

Answer 32

Air pollution is higher in urban areas due to dense traffic emissions, industrial activities, and energy use, which release large amounts of carbon dioxide, nitrogen oxides, and particulates. Limited air circulation caused by tall buildings further prevents pollutants from dispersing, concentrating them within city boundaries. In simple terms: More cars and factories in cities cause more air pollution.

Question 33

Why may nighttime temperatures vary across a city?

Answer 33

Nighttime temperatures can vary across a city due to differences in surface materials and heat retention. Urban structures like asphalt and concrete absorb and store heat during the day, slowly releasing it at night. Areas with less vegetation and higher building density tend to remain warmer, while parks and green spaces cool down more quickly. In simple terms: Roads and buildings keep cities warmer at night.

Question 34

How does the climate in urban areas differ from that in the surrounding countryside?

Answer 34

Urban climates are typically warmer, drier, and more polluted than surrounding rural areas. This is due to the urban heat island effect, reduced vegetation, higher emissions from vehicles and industries, and altered wind patterns caused by buildings. Urban areas also experience more localized rainfall and thunderstorms due to rising warm air and pollutants acting as condensation nuclei. In simple terms: Cities are hotter, drier, and have more pollution than the countryside.

Question 35

Why do urban areas often experience warmer, wetter conditions and more fog than surrounding rural areas?

Answer 35

Urban areas retain more heat due to asphalt, concrete, and limited vegetation, creating warmer conditions. Increased emissions from traffic and industry provide condensation nuclei for water vapor, enhancing cloud formation and precipitation. The combination of heat and moisture often leads to fog, especially when warm air meets cooler ground surfaces. In simple terms: Cities are warmer and have more pollution, which makes them wetter and foggier.