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Global Climate Change 01:50

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Throughout its ~4.5 billion year history, the Earth has experienced periods of warming and cooling. However, the current drastic increase in global temperatures is well outside of the Earth’s cyclic norms, and evidence for human-caused global climate change is compelling. Paleoclimatology, the study of ancient climate conditions, provides ample evidence for human-caused global climate change by comparing recent conditions with those in the past.

Past Periods of Warming and Cooling

In...

What is Weather? 01:07

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Overview

Weather refers to the current state of atmospheric conditions at a specific time and place. Weather is temporary and is influenced by the interactions between the sun, atmosphere (gases around the Earth), hydrosphere (the water bodies of the Earth), and geosphere (the land portion of the Earth). As all of these factors differ across location and time, different weather can be observed across the planet.

Solar Radiation and the Greenhouse Effect

Solar radiation penetrates the...

What is Climate? 01:16

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Climate refers to the prevailing weather conditions in a specific area over an extended period. As the saying goes, “Climate is what you expect. Weather is what you get.” Climate is influenced by geographic factors, such as latitude, terrain, and proximity to bodies of water.

Weather and Climate

Weather and climate are related, though they differ in terms of time scale and predictability. Weather refers to the state of the atmosphere at a specific time and place, whereas climate...

Frequency-dependent Selection 01:21

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When the fitness of a trait is influenced by how common it is (i.e., its frequency) relative to different traits within a population, this is referred to as frequency-dependent selection. Frequency-dependent selection may occur between species or within a single species. This type of selection can either be positive—with more common phenotypes having higher fitness—or negative, with rarer phenotypes conferring increased fitness.

Positive Frequency-Dependent Selection

In positive...

Patterns of Fever 01:26

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Before understanding the types and patterns of fever, it is essential to know its phases.

• The first stage is the onset/invasion phase, during which the body temperature rises. It might be a sudden or gradual process.
• The second stage is the steady phase, during which the body temperature has reached its maximum and remains constant at a high level.
• The third stage is the defervescence or decline phase, during which the elevated temperature returns to...

Ecological Disturbance 02:26

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An ecological disturbance is a temporary disruption in the environment resulting from abiotic, biotic, or anthropogenic factors, causing a pronounced change in an ecosystem. The impact of an ecological disturbance, which can depend on its intensity, frequency, and spatial distribution, plays a significant role in shaping the species diversity within the ecosystem.

Ecological disturbances can be caused by an event as small as the trampling of underbrush to an incident as wide-ranging as a...