climate science midterm 1 study guide!

What percentage of Earth's water is readily accessible freshwater, and why is this significant for human populations?

Less than 1% of Earth's water is readily accessible freshwater found in lakes, rivers, and other surface forms. This is significant because humans and many other living things rely on this small percentage for survival and various needs like agriculture and industry.

Describe the concept of residence time in the context of the water cycle. Give two examples of water reservoirs with significantly different residence times.

Residence time is the average time an individual water molecule spends in a particular water reservoir. For example, water in oceans has a long residence time of about 4,000 years, while water in the atmosphere has a very short residence time of about 1.5 weeks.

Explain how the Sun's energy drives the water cycle. Name and briefly describe two key processes involved.

The Sun's energy drives the water cycle by providing the heat needed for evaporation, where liquid water turns into water vapor, and sublimation, where ice directly turns into water vapor. These processes move water from the Earth's surface into the atmosphere.

What is groundwater, and where is it typically found? How do humans access this important freshwater resource?

Groundwater is freshwater found underground in the pores between soil particles and in the cracks of rocks. Humans often access groundwater by digging wells that tap into groundwater reservoirs called aquifers.

Define albedo and explain its relevance to Earth's temperature. Provide an example of a change that would decrease Earth's albedo.

Albedo is the fraction of light that is reflected away from a body. It is relevant to Earth's temperature because a higher albedo means more solar radiation is reflected back into space, leading to a cooler planet, while a lower albedo means more radiation is absorbed, leading to a warmer planet. Melting snow and ice would decrease Earth's albedo.

What is the greenhouse gas effect, and why is it essential for life on Earth? Briefly describe how greenhouse gases interact with infrared radiation.

The greenhouse gas effect is the process by which certain gases in Earth's atmosphere absorb and re-emit infrared radiation, trapping heat and warming the planet. This effect is essential for life as it keeps Earth's temperature within a habitable range; without it, the Earth would be frozen.

Explain the concept of partial pressure in the context of atmospheric gases. Provide an example using nitrogen.

Partial pressure is the fraction of the total atmospheric pressure exerted by a particular gas, which is proportional to the fraction of molecules that gas occupies. For example, nitrogen makes up 78% of the atmosphere, so its partial pressure is approximately 0.78 atm.

why are gases with lower partial pressures, like carbon dioxide, a significant concern as greenhouse gases, despite water vapor being more abundant?

Despite water vapor being the most abundant greenhouse gas, gases like carbon dioxide are a major concern because they have lower partial pressures. According to band saturation, at higher concentrations, increasing abundant GHGs has a smaller impact, meaning that changes in less abundant GHGs can have a more significant effect on absorbing radiation.

Describe two ways in which human activities have increased the availability of freshwater in some regions.

Humans have increased freshwater availability through technologies such as digging wells to access groundwater and using desalination, a process that removes salt from ocean water to produce fresh water. Rainwater harvesting is another method used to collect and store precipitation.

Explain how the water cycle plays a role in the cycling of other elements on Earth. Provide one example from the text.

The water cycle plays a crucial role in the cycling of other elements because rainfall and surface runoff help to move elements from terrestrial ecosystems to aquatic ecosystems. For instance, surface runoff can carry carbon, nitrogen, phosphorus, and sulfur into rivers, lakes, and oceans.

Freshwater

Water that has a low concentration of dissolved salts and other total dissolved solids.

Saltwater

Water with a high concentration of dissolved salts, primarily sodium chloride, found in oceans and some lakes.

Water Cycle (Hydrologic Cycle)

The continuous movement of water on, above, and below the surface of the Earth.

Residence Time

The average length of time a water molecule stays in a particular water reservoir.

Groundwater

Water found underground in the spaces between soil particles and in the cracks of rocks

Aquifer

An underground layer of permeable rock or sediment that holds groundwater and can be extracted through wells.

Evaporation

The process by which water changes from a liquid to a gas (water vapor).

Sublimation

The process by which a solid (like ice or snow) changes directly into a gas (water vapor) without becoming a liquid.

Condensation

The process by which water vapor in the air changes into liquid water, often forming clouds.

Precipitation

Any form of water that falls from clouds to the Earth's surface, such as rain, snow, sleet, or hail.

Infiltration

The process by which water on the ground surface enters the soil.

Percolation

The downward movement of water through the soil and rock due to gravity.

Runoff

Water that flows over the land surface and does not infiltrate into the ground

Transpiration

The process by which moisture is carried through plants from roots to small pores on the underside of leaves, where it changes to vapor and is released to the atmosphere.

Albedo

The fraction of incident radiation (like sunlight) that is reflected by a surface.

Electromagnetic Radiation (EM)

Energy that travels in the form of waves, encompassing a wide spectrum including visible light, infrared radiation, and ultraviolet radiation.

Wavelength

The distance between successive crests (or troughs) of a wave.

Frequency

The number of waves that pass a fixed point per unit of time.

Infrared Radiation (IR)

A type of electromagnetic radiation with longer wavelengths than visible light, often associated with heat.

Blackbody Radiation

The thermal electromagnetic radiation emitted by all objects with a temperature above absolute zero.

Greenhouse Gas

A gas in the atmosphere that absorbs and emits infrared radiation, trapping heat and contributing to the greenhouse effect.

Atmospheric Pressure

The force per unit area exerted by the weight of the atmosphere above a given point.

Partial Pressure

The pressure that would be exerted by one of the gases in a mixture if it occupied the same volume alone.

Band Saturation

The phenomenon where, at higher concentrations of a greenhouse gas, the addition of more gas has a progressively smaller effect on the absorption of infrared radiation.

Climate Sensitivity

A measure of how much the global mean temperature will increase in response to a doubling of atmospheric carbon dioxide concentrations.

Biogeochemical Cycle

The pathways by which chemical elements or molecules move through the biotic (living) and abiotic (non-living) components of Earth's systems.

Explain the role of greenhouse gases (GHGs) in Earth's climate system.

Greenhouse gases (GHGs) absorb and re-emit infrared (thermal) radiation emitted by the Earth's surface. This process traps heat within the atmosphere, keeping the planet at a habitable temperature. Even small changes in GHG concentrations can significantly alter the amount of radiation absorbed.

Describe why water's high heat capacity is important for stabilizing Earth's temperatures and climate.

Water's high heat capacity means it takes a significant amount of energy to change its temperature. This property helps to stabilize Earth's temperatures because oceans absorb and release heat slowly, moderating temperature fluctuations compared to land.

What is the Earth's albedo, and how does it relate to incoming and outgoing radiation?

Earth's albedo is the measure of how much incoming solar radiation is reflected back into space. Areas with high albedo (like ice or clouds) reflect a large portion of sunlight, while areas with low albedo (like oceans or forests) absorb more.

Differentiate between sensible heat and latent heat in the context of atmospheric energy transfer.

Sensible heat is the heat we can feel as temperature and is associated with the kinetic energy of air molecules. Latent heat is the energy stored or released when water changes phase (e.g., from liquid to gas or gas to liquid) without a change in temperature.

Explain how convection cells in the atmosphere are formed and the general direction of air movement within them.

Convection cells are formed due to the uneven heating of the Earth's surface. Warm, less dense air rises, while cold, denser air sinks, creating a circular movement. Air flows from areas of high pressure (where air is sinking) to areas of low pressure (where air is rising).

Describe the Coriolis effect and how it influences the movement of air in the Northern Hemisphere.

The Coriolis effect is caused by the Earth's rotation, which results in a deflection of moving objects (including air) to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. This deflection is more pronounced at higher latitudes due to the varying rotational speeds.

Name and briefly describe the three types of atmospheric circulation cells that are formed due to the Coriolis effect.

The three atmospheric circulation cells are Hadley, Ferrel, and Polar cells. Hadley cells are thermally driven, with warm air rising at the equator and sinking at around 30 degrees latitude. Ferrel cells are driven by the movement of air in the Hadley and Polar cells and exist between 30 and 60 degrees latitude. Polar cells are also thermally driven, with cold air sinking at the poles and rising at around 60 degrees latitude.

How do the atmospheric circulation cells influence the distribution of different biomes across latitudes?

Atmospheric circulation cells create distinct patterns of rising and sinking air, which influence temperature and precipitation. Rising air in the Hadley and Polar cells leads to precipitation and often rainforests or low-pressure zones, while sinking air in the Hadley cells leads to dry conditions and deserts at subtropical latitudes.

Explain the mechanism behind monsoon systems and the key differences between summer and winter monsoons.

Monsoon systems are driven by the difference in heat capacity between land and water. During summer, land heats up faster than the ocean, creating a low-pressure area over land that draws in moist air from the cooler ocean, leading to heavy rainfall. This process reverses in winter when the ocean is warmer than the land.

Describe the process of orographic precipitation and the formation of rain shadows.

Orographic precipitation occurs when moist air is forced to rise as it encounters a mountain range. As the air rises, it cools, and water vapor condenses and falls as precipitation on the windward side of the mountain. The air that descends on the leeward side is drier, often creating a rain shadow with arid conditions.

Heat Capacity

The amount of heat energy required to raise the temperature of a substance by a specific amount.

Sensible Heat

The transfer of thermal energy that results in a change in temperature and can be felt.

Latent Heat

The energy absorbed or released during a change in the phase of a substance (e.g., water vapor to liquid water) without a change in temperature.

Troposphere

The lowest layer of Earth's atmosphere, where most weather occurs and where water vapor is concentrated.

Meridional

Relating to or running in a north-south direction (latitude)

Zonal

Relating to or running in an east-west direction (longitude).

Westerlies

Prevailing winds that blow from west to east in the middle latitudes.

Easterlies

Prevailing winds that blow from east to west in the tropics and polar regions.

Coriolis Effect

An apparent deflection of moving objects (like air and water) to the right in the Northern Hemisphere and to the left in the Southern Hemisphere due to Earth's rotation. This occurs because the ground beneath the air moves faster at lower latitudes than at higher latitudes.

Hadley Cell

A thermally driven atmospheric circulation cell in the low latitudes (approximately 0-30 degrees), characterized by rising air at the equator and sinking air in the subtropics.

Ferrel Cell

An atmospheric circulation cell in the middle latitudes (approximately 30-60 degrees), driven by the movement of the Hadley and Polar cells.

Polar Cell

A thermally driven atmospheric circulation cell in the high latitudes (approximately 60-90 degrees), characterized by sinking cold air at the poles and rising air at lower latitudes.

Baroclinic Instability

A process in fluid dynamics that can lead to the development of mid-latitude cyclones and weather systems, often associated with fast-moving jet streams.

Monsoon System

A seasonal reversal of wind direction, often accompanied by significant changes in precipitation, driven by the differential heating of land and ocean.

Orographic Precipitation

Precipitation that occurs when moist air is forced to rise over a mountain range, causing it to cool and condense.

Rain Shadow

A dry area on the leeward (downwind) side of a mountain range, resulting from the loss of moisture as air rises and precipitates on the windward side.

Describe the primary characteristics of the Intertropical Convergence Zone (ITCZ) and its location.

The ITCZ is a zone of high precipitation located near the equator (approximately 0° latitude) where warm, moist air rises. This rising air is associated with the convergence of surface winds (easterly trade winds) from both hemispheres.

What is the main driving force behind the Ferrel cell's circulation? How does this differ from the Hadley and Polar cells?

The Ferrel cell is primarily driven by the movement of the adjacent Hadley and Polar cells, rather than direct temperature gradients. Its ascending and descending branches are a consequence of these larger-scale circulations, making it a weaker cell.

Explain the Ekman spiral and the direction of net water transport relative to the wind in the Southern Hemisphere.

The Ekman spiral describes the spiraling change in the direction of water currents with increasing depth due to the Coriolis effect and friction. In the Southern Hemisphere, each subsequent layer of water moves to the left of the layer above, resulting in a net water transport approximately 90 degrees to the left of the surface wind direction.

What are gyres, and what is the primary mechanism responsible for their formation in the oceans?

Gyres are large, rotating systems of ocean currents formed by the combination of wind patterns (driven by atmospheric circulation cells) and the Coriolis effect. Ekman transport plays a key role in converging surface waters towards the center of these gyres.

Describe the process of coastal upwelling and the conditions that typically lead to its occurrence.

Coastal upwelling occurs when surface winds blow along a coastline, causing Ekman transport to move surface water away from the shore. This creates a "vacuum" that allows colder, nutrient-rich deep water to rise to the surface.

What are the two main factors that influence the density of seawater and drive thermohaline circulation?

The two main factors that influence the density of seawater are temperature and salinity. Cold water is denser than warm water, and saltier water is denser than less salty water.

Explain how ice formation near the poles contributes to the salinity and density of surrounding ocean water.

When seawater freezes to form ice, the salt is excluded from the ice crystal structure and is concentrated in the remaining liquid water. This process increases the salinity and therefore the density of the surrounding water, causing it to sink.

During a typical El Niño event, how does the sea surface temperature in the eastern equatorial Pacific change, and what causes this change?

During an El Niño event, the sea surface temperature in the eastern equatorial Pacific becomes warmer than average. This is caused by a weakening or reversal of the equatorial trade winds, which allows the warm water that has accumulated in the western Pacific to surge eastward, suppressing the usual upwelling of cold water.

Briefly describe the Walker circulation and how it is affected during La Niña conditions.

The Walker circulation is a zonal (east-west) atmospheric convection cell over the equatorial Pacific, with rising air in the west and sinking air in the east. During La Niña conditions, the temperature contrast between the east and west Pacific is enhanced due to increased upwelling in the east, leading to a stronger Walker circulation.

ITCZ (Intertropical Convergence Zone)

A zone of low atmospheric pressure near the equator where the trade winds from the Northern and Southern Hemispheres converge, resulting in significant precipitation.

Easterly Trade Winds

Surface winds blowing from east to west found in the tropics (between approximately 30 degrees latitude and the equator).

Polar Easterlies

Surface winds blowing from east to west found in the high latitudes (between approximately 60 and 90 degrees latitude).

Ekman Spiral

A model describing the directional change of ocean currents with depth caused by wind stress and the Coriolis effect, resulting in a net transport of water perpendicular to the wind direction.

Gyre

A large system of rotating ocean currents, typically driven by global wind patterns and the Coriolis effect.

Western Intensification

The phenomenon where western boundary currents of ocean gyres are stronger, narrower, and deeper than eastern boundary currents due to the variation of the Coriolis effect with latitude.

Upwelling

The process where deep, cold, nutrient-rich water rises towards the surface, often caused by wind-driven surface water divergence.

Downwelling

The process where surface water sinks towards the deeper ocean, often caused by wind-driven surface water convergence.

Thermohaline Circulation

A global pattern of ocean circulation driven by differences in water density, which are caused by variations in temperature (thermo) and salinity (haline). Also known as the ocean conveyor belt.

ENSO (El Niño Southern Oscillation)

A periodic and irregular variation in winds and sea surface temperatures over the tropical Pacific Ocean, with major implications for weather and climate around the globe.

El Niño

The warm phase of ENSO, characterized by warmer-than-average sea surface temperatures in the central and eastern equatorial Pacific.

La Niña

The cool phase of ENSO, characterized by colder-than-average sea surface temperatures in the central and eastern equatorial Pacific.

Walker Circulation

An atmospheric circulation pattern over the tropical Pacific Ocean, characterized by rising air in the west and sinking air in the east during normal conditions.

Describe the role of wind and tides in surface ocean transport and explain how the Coriolis effect influences ocean currents.

In the surface ocean, winds are the dominant force driving transport, though tides are important in coastal areas. The Coriolis effect causes these currents to be deflected to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.

What factors drive transport in the deep ocean, and how does water density change as it moves towards the poles?

Density changes, influenced by temperature and salinity, drive transport in the deep ocean. As water moves towards the poles, it becomes colder and saltier (due to sea ice formation), increasing its density and causing it to sink.

Explain the El Niño-Southern Oscillation (ENSO) and describe its general effects on global surface temperatures.

ENSO is an interaction between atmospheric and oceanic circulation in the equatorial Pacific that occurs on 3-8 year cycles and affects global temperatures. El Niño events, characterized by the spreading of warm upwelling waters eastward, generally lead to hotter global average temperatures.

Why is carbon considered a fundamental building block of life, and what are some of the inorganic and organic forms it can take?

Carbon can form many bonds with various elements, making it essential for the complex molecules that constitute life. Inorganic forms include limestone (CaCO3) and dissolved carbonate ions (HCO3-, CO3^2-), while organic forms include methane (CH4), sugars, proteins, and fats.

Define "residence time" in the context of carbon reservoirs and provide the approximate size of the atmosphere, land plants, and deep ocean carbon reservoirs in Pg.

Residence time is the average amount of time something spends in a reservoir, calculated as reservoir size divided by the fluxes in and out (assuming a steady state). The atmosphere holds approximately 750 Pg of carbon, land plants store about 650 Pg, and the deep ocean contains roughly 37,000 Pg.

Explain the process of photosynthesis and its significance in the short-term carbon cycle, including an estimate of the amount of atmospheric CO2 it draws down annually.

Photosynthesis is the process by which plants convert atmospheric CO2 into organic matter using sunlight for energy. It represents half of the short-term carbon fluxes, drawing down approximately 16% (120 Pg/yr) of atmospheric CO2 annually and removing about 25% of human CO2 emissions.

Describe the process of respiration in plants and soils, and explain how soil temperature influences soil respiration rates.

Plant respiration breaks down organic carbon in plant cells, releasing CO2 to the atmosphere. Soil respiration involves the decomposition of plant material in soils by microbes, fungi, worms, and bugs, also releasing CO2. Higher soil temperatures generally lead to increased rates of soil respiration.

Explain how atmospheric carbon dioxide dissolves in the ocean and the initial chemical reaction that occurs.

Atmospheric carbon dioxide (CO2) dissolves in seawater. Some of this dissolved CO2 reacts with water (H2O) to form carbonic acid (H2CO3), which then dissociates into bicarbonate (HCO3-) and hydrogen ions (H+), leading to ocean acidification.

State Henry's Law in relation to gas solubility in liquids and explain how rising atmospheric CO2 affects the ocean's uptake of carbon.

Henry's Law states that at a constant temperature, the amount of a gas that dissolves in a liquid is directly proportional to the partial pressure of that gas in equilibrium with the liquid. Therefore, as atmospheric CO2 levels rise, the ocean has the capacity to absorb more CO2.

Describe the general pattern of carbon dioxide absorption and release in the ocean in relation to upwelling and downwelling zones.

Generally, carbon dioxide is absorbed by the ocean in downwelling and cooling zones, where surface waters sink and take dissolved gases with them. Conversely, CO2 is generally released from the ocean in upwelling zones, where deep, carbon-rich waters rise to the surface.

Short-Term Carbon Cycle

The movement of carbon between the atmosphere, land biosphere (including plants and soils), and oceans on time scales ranging from years to centuries.

Carbon Reservoir

A location where carbon is stored, such as the atmosphere, oceans, land plants, and soils.

Flux

The rate at which carbon moves between different reservoirs, typically measured in petagrams of carbon per year (Pg/yr).

Photosynthesis

The process by which green plants and some other organisms use sunlight to synthesize foods with the help of chlorophyll. Carbon dioxide and water are converted into glucose (a sugar) and oxygen.

Respiration

The process by which organisms break down organic matter (like sugars) to release energy, producing carbon dioxide as a byproduct. This occurs in plants, animals, and decomposers like microbes and fungi.

Residence Time (carbon cycle)

The average amount of time a carbon atom spends in a particular reservoir. It is calculated as the size of the reservoir divided by the total rate of carbon entering or leaving it (assuming a steady state).