Glossary

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Term Term description
paleoclimate

Climates in the geological past.

paleoclimatology

Paleoclimatology is the study of past climates. It is a multidisciplinary field combining history, anthropology, archaeology, chemistry, physics, geology, atmospheric, and ocean sciences.

particulate matter

Complex mixture of extremely small particles and liquid droplets in the air. Particle pollution is made up of a number of components, including acids (such as nitrates and sulfates), organic chemicals, metals, and soil or dust particles.

pastoral letters

An official letter of religious instruction from a Roman Catholic bishop or group of bishops to all the clergy and members of Church under their jurisdiction.

peat

Peat is a heterogeneous mixture of partially decomposed plant (humus) material that has accumulated in a water-saturated environment and in the absence of oxygen. The warmer the climate, the quicker the plant material will decompose. It can be used as fuel after dried, and is a precursor to fossil fuel in the process of coal formation.

percolation

The slow passage of a liquid through a filtering medium such as the percolation of rainwater through the soil.

perennial

 

Lasting for an indefinitely long time; plants that live for more than two years.

 

periodic table

A table that lists all of the known chemical elements on Earth, arranged according to their properties. It can be used to predict how they will react with other elements.

permafrost


A layer of water-logged soil or bedrock that has been continuously frozen for at least two years and as long as tens of thousands of years. Permafrost can reach depths of up to 1,524 m (4,999 ft). It is predominantly found in the tundra biome and throughout most of the polar regions and underlies about one fifth of the Earth's land surface.

permanent components

The atmosphere contains consistent components such as Nitrogen and Oxygen that play an essential role in the protection and functioning of the planet.

permeable

The ability of a material to allow the passage of a liquid, such as water. Permeable materials, such as gravel and sand, allow water to move quickly through them whereas unpermeable material, such as clay, does not allow water to pass through.

phenology

The scientific study of periodic biological phenomena, such as flowering, breeding, and migration, in relation to climatic conditions.

phenotype

The physical traits and appearance of an organism that are coded by its genetic makeup. The phenotype of an organism depends on which genes are dominant and on the interaction between genes and environment.

photoelectric effect

The emission of free electrons from a metal surface when sufficiently energetic light strikes it.

photons

The smallest particle of light or other electromagnetic energy, having no mass and no electric charge.

photoperiod

The interval in a 24-hour period during which a plant or animal is exposed to light.

photosynthesis

The biochemical process by which green plants and some bacteria capture light energy and use it to produce chemical energy. Carbon dioxide and water are consumed during photosynthesis while oxygen and simple sugars are produced.

photovoltaic cells

A cell that converts solar energy into electrical energy.

photovoltaic effect

The effect observed when electromagnetic radiation, especially visible light from the sun, falls on a thin film of one solid deposited on the surface of a dissimilar solid producing a difference in potential between the two materials.

phyla

The primary subdivision of a taxonomic kingdom, grouping together all classes of organisms that have the same body plan.

phytochemicals

Bioactive chemical compounds found in plants. Many phytochemicals have medicinal properties, and others are important sources of vitamins.

phytoplankton

 

Microscopic, free-floating, autotrophic organisms that function as primary producers in aquatic ecosystems.

 

Planetary Commons

Physical space that includes the Earth processes, habitats and natural goods needed for biotic sustenance and well-being.

planktivorous

An aquatic organism that feeds on planktonic food, including zooplankton or phytoplankton. Planktivores can be microscopic in size or as large as the baleen whales that feed on plankton.

 

plankton

 

Primarily microscopic organisms that occupy the upper water layers in both freshwater and marine ecosystems, and include autotrophic (phytoplankton) and heterotrophic (zooplankton, bacteria, and protozoans).

 

planktonic

 

Organisms whose habitat is the open water of oceans or lakes.

 

plate tectonics

The movement of large plates on the Earth's crust driven by convection in the Earth's mantle, the semi-liquid layer of superheated rock below the crust. Plate tectonics are responsible for volcanoes, earthquakes, and contribute to long-term changes in climate, and the current distribution of biological species on Earth.

polar desert

 

A biome with precipitation below 250 millimeters per year and with a mean temperature during the warmest month of less than 10 degrees Celsius.

 

polar front

The region or boundary separating air masses of polar origin from those of tropical or subtropical origin.

pollination

The process by which the male sex cells in flowering plants (pollen) are transferred from the male part (anther) to the female part (stigma) of the flower. Pollination leads to fertilization and the creation of new seeds that grow into new plants. Most plants are pollinated by insects looking for nectar in the flower, or by animals or wind.

pollution

Presence of matter (gas, liquid, solid) or energy (heat, noise, radiation) whose nature, location, or quantity causes (or has the potential to cause) damage to the condition, health, safety, or welfare of animals, humans, plants, or property. Toxic materials in the environment.

polyp

A sedentary and simple aquatic animal form characterized by a more or less fixed base, columnar body, and free end with mouth and tentacles, especially as applied to coelenterates.

population

 

A group of individuals of the same species living in the same geographic area.

 

positive feedback

A positive feedback in a system is where the effect reinforces the cause. This means that the impact will go on increasing. With climate change, for example, when surface temperature increases, it leads to melting of ice. Water is more absorbent to sunlight than ice. This causes more sunlight to be absorbed by Earth, which further increases the temperature.

potable water

Water that is safe for humans to drink, uncontaminated by bacteria or other disease causing pathogens, or by toxic chemicals.

potable water

Water that is safe for humans to drink, uncontaminated by bacteria or other disease causing pathogens, or by toxic chemicals.

potential energy

Energy stored in a system of forcefully interacting physical entities.

potential energy

Energy stored within an object due to its position in a force field (as in gravitational potential energy) or because of its structure (as in chemical or nuclear energy).

power

The rate at which work is done or the rate at which energy is consumed.

precession

The slow, conical motion of the earth's axis of rotation, caused by the gravitational attraction of the sun and moon, and, to a smaller extent, of the planets, on the equatorial bulge of the earth. 12,000 years from now the Northern Hemisphere will experience summer in December and winter in June because the axis of the earth will be pointing at the star Vega instead of its current alignment with the North Star of Polaris.

precession

The change in orientation of the rotational axis of a rotating body.

precipitation

The part of the hydrologic cycle in which the water vapor in the atmosphere condenses and falls to Earth as rain or snow.

preferential option of care for the poor

 

The moral principle that people in absolute need of the basic goods of life should be given priority in caregiving.

 

preservation

The protective setting aside of natural resources to prevent damage caused by human activities such as logging, mining, hunting, and fishing.

primary consumer

Organisms that feed on green plants or other autotrophic organisms.

primary producer

Organism (autotroph) at the bottom of a food chain that produces its own food using photosynthesis or chemosynthesis, and is a food source for primary consumers (herbivores).

protein

Any of a group of complex organic macromolecules that contain carbon, hydrogen, oxygen, nitrogen, and usually sulfur and are composed of one or more chains of amino acids. Proteins are fundamental components of all living cells and include many substances, such as enzymes, hormones, and antibodies, that are necessary for the proper functioning of an organism. They are essential in the diet of animals for the growth and repair of tissue and can be obtained from foods such as meat, fish, eggs, milk, and legumes.

proton

A stable subatomic particle that has a positive electric charge and is part of the nucleus of an atom. Its charge is opposite to that of an electron but is equal in magnitude. A proton's mass is 1,836 times that of an electron.

prudence

The moral virtue of good decision-making with respect for all circumstances.

pyrite

A silver to yellow, metallic mineral consisting of iron and sulfur. It is used as a source of iron and in making sulfur dioxide. Because of its shiny look and often yellow color, it is sometimes mistaken for gold and for this reason is also called fool's gold.

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