6.1 Introduction to the Atmosphere (DP IB Environmental Systems & Societies (ESS): HL): Flashcards

Convection in the atmosphere is the process where warm air rises and cool air sinks, creating vertical movement of air.

The two key layers of the atmosphere for living systems are the troposphere and the stratosphere.

The ozone layer is found in the stratosphere and its function is to absorb and block most of the Sun's harmful ultraviolet (UV) radiation.

The troposphere is the lowest layer of the atmosphere, extending up to about 10 km from Earth's surface, where weather phenomena and most gas mixing occur.

The stratosphere extends from about 10 km to 50 km above the Earth's surface.

Differential heating of the atmosphere is caused by the Sun heating the Earth and its atmosphere unevenly, with the equator receiving more direct sunlight and the poles less.

A greenhouse gas is a gas in the atmosphere that traps heat by absorbing and re-emitting infrared radiation, helping to warm the Earth.

The greenhouse effect is the process by which greenhouse gases in the Earth's atmosphere trap heat, keeping the planet warm enough to support life.

The most abundant greenhouse gas in Earth's atmosphere is water vapour.

An aerosol is a tiny particle or droplet suspended in the atmosphere, which can influence climate by absorbing or reflecting sunlight.

Nitrous oxides have the greatest warming effect per molecule, being nearly 300 times more potent than carbon dioxide.

Greenhouse gases trap thermal energy in the atmosphere by absorbing and re-emitting infrared radiation.

Two main sources of methane in the atmosphere are agriculture (especially livestock digestion) and natural gas extraction (methane leaks).

Black carbon is a type of aerosol produced from incomplete combustion of fossil fuels, wood, or biomass. It absorbs sunlight and warms the atmosphere.

The main source of carbon dioxide in the atmosphere is the burning of fossil fuels.

False.

The greenhouse effect is a natural process necessary for life on Earth. Human activity accelerates the effect, causing global warming.

The average surface temperature of the Earth is about 15 °C, but without the greenhouse effect, it would be about -18 °C.

Greenhouse gases act like a blanket by allowing sunlight to pass through but trapping infrared radiation, reducing heat loss into space.

The greenhouse effect is a natural process in which certain gases in the atmosphere trap heat, keeping the Earth warm enough to support life by preventing some thermal energy from escaping into space.

A dynamic system is a system that is constantly changing due to continuous physical and chemical processes over time.

Earth's atmosphere is composed of various gases, layers (such as the troposphere and stratosphere), each with distinct characteristics.

The atmosphere is surrounded by several layers, each having distinct characteristics.

The characteristics of the different layers of the atmosphere result from continuous physical and chemical processes occurring over time.

The enhanced greenhouse effect is the intensified trapping of heat in the atmosphere due to increased greenhouse gases from human activities.

False.

The natural greenhouse effect is necessary as it helps maintain a habitable climate on Earth.

The enhanced greenhouse effect is caused by human activities releasing too many greenhouse gases into the atmosphere.

Increasing greenhouse gas concentrations intensifies heat trapping in the atmosphere, which leads to global warming.

A convection current is the movement of air caused by warmer, less dense air rising and cooler, denser air sinking, driving wind patterns and weather systems.

Warm air is less dense and rises, while cold air is more and sinks.

The tricellular model explains how convection currents in the atmosphere create three major cells in each hemisphere, influencing global wind patterns.

Ozone is a molecule composed of three oxygen atoms (O₃), mainly found in the stratosphere, that absorbs harmful ultraviolet radiation from the Sun.

Ozone protects life by absorbing ultraviolet (UV) radiation from the Sun, preventing most of it from reaching Earth's surface.

The atmosphere is a collection of layers of gases that surround the Earth and are held in place by gravity.

Gravity keeps the layers of gases that make up the atmosphere in place by pulling atmospheric molecules towards the Earth's surface.

Air is denser at lower altitudes because gravity pulls atmospheric molecules towards the Earth's surface.

False.

As altitude increases, the strength of gravitational pull decreases because gravitational force is inversely proportional to distance from the Earth.

Atmospheric thinning is the gradual decrease in air density as altitude increases, meaning there are fewer molecules in a given volume of air at higher altitudes.

At sea level, the atmosphere is dense, containing a higher concentration of oxygen and other gases than at high altitudes.

Climbers on Mount Everest need to use oxygen tanks because the air at high altitudes is much thinner, with much lower oxygen levels.

The standard lapse rate is the average rate at which temperature decreases by about 1 degree Celsius for every 100 metres of altitude gained.

Milankovitch cycles are three long-term changes in Earth's position and movement relative to the Sun that affect the amount of solar radiation Earth receives and influence climate over tens of thousands of years.

Milankovitch cycles change the amount of solar radiation reaching Earth, which affects the climate over very long timescales such as tens to hundreds of thousands of years.

Milankovitch cycles contribute to natural climate patterns such as ice ages and warmer interglacial periods.

Eccentricity is the shape of Earth's orbit around the Sun, which changes from more circular to more elliptical over a cycle of about 100,000 years.

A more circular orbit leads to milder seasonal differences, allowing ice sheets to build up over time and increasing the likelihood of glaciation.

The cycle of eccentricity lasts about 100,000 years.

Obliquity is the tilt of Earth's axis in relation to its orbit around the Sun, changing between about 22.5° and 24.5° over a 41,000-year cycle.

A higher axial tilt increases the intensity of seasons, making summers warmer and winters colder, which reduces polar ice buildup.

Obliquity causes the angle of Earth's axis to change from about 22.5° to 24.5°.

Precession is the wobble in Earth's rotational axis, which changes the timing of the seasons over a cycle of about 26,000 years.

True.

Precession changes when each season occurs in Earth's orbit, altering how solar radiation is distributed between the seasons.

The precession cycle takes approximately 26,000 years.

The Hothouse Earth concept refers to a future state where the Earth's climate becomes much hotter than the natural variability of the past, due to self-amplifying warming and positive feedback loops.

The Quaternary period began 2.5 million years ago and was characterised by alternating ice ages and warmer interglacial periods.

Current climate change is driven by human activities and is unprecedentedly rapid, whereas natural climate changes in the past occurred over tens to hundreds of thousands of years.

The Anthropocene epoch is a proposed new geological time period marked by significant human impact on Earth's climate and environment. Some scientists suggest we have entered it because human activity is now the dominant influence on climate and ecosystems.

In the Hothouse Earth scenario, Earth's average temperature rises irreversibly to 4 to 5 °C above pre-industrial levels.

A climate tipping point is a threshold where a small change can trigger significant and often irreversible shifts in the Earth's climate system.

False.

Positive feedback mechanisms amplify global warming and its effects, leading to even more warming.

Two examples are the melting of ice (which darkens the Earth's surface) and the release of methane from thawing permafrost, both of which intensify warming.

The pre-biotic atmosphere refers to Earth's early atmosphere before life existed, which contained high levels of carbon dioxide and methane, little or no oxygen, and high concentrations of nitrogen.

The lack of oxygen in Earth's early atmosphere meant there was no protective ozone layer.

Early Earth's atmosphere contained high levels of carbon dioxide and methane, but very little oxygen.

Photosynthesis is the process by which certain organisms, such as cyanobacteria, use sunlight to convert carbon dioxide and water into glucose and oxygen.

True.

Cyanobacteria developed photosynthesis and released oxygen into the atmosphere, leading to a gradual increase in atmospheric oxygen levels.

The formation of the ozone layer in the stratosphere protected early life from harmful UV radiation.

Banded iron formations (BIFs) are layers of iron oxides that settled on ancient ocean floors when oxygen produced by photosynthetic organisms reacted with dissolved iron. They provide geological evidence for the early oxygenation of Earth's atmosphere and oceans.

The rise of oxygen led to the formation of the ozone layer, which absorbed harmful UV radiation and made life on land possible. Oxygen also enabled the evolution of aerobic respiration and more complex, energy-demanding organisms.

Aerobic respiration is a process in which organisms use oxygen to release energy from food, producing carbon dioxide and water as waste products. It is more efficient than anaerobic respiration.

The evolution of life on Earth significantly changed the composition of the atmosphere, especially by increasing the amount of oxygen.