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01:50Global Climate Change
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.
01:19Mechanism of heat transfer
Understanding heat transfer mechanisms is essential for understanding how our bodies maintain balance in different environmental conditions. When the environment is thermoneutral, the body is in a state of balance, neither using nor releasing energy to maintain its core temperature. However, when the environment is not thermoneutral, the body employs four heat transfer mechanisms to maintain homeostasis: conduction, convection, evaporation, and radiation. These mechanisms facilitate heat...
01:20Mechanisms of Heat Transfer II
In convection, thermal energy is carried by the large-scale flow of matter. Ocean currents and large-scale atmospheric circulation, which result from the buoyancy of warm air and water, transfer hot air from the tropics toward the poles and cold air from the poles toward the tropics. The Earth’s rotation interacts with those flows, causing the observed eastward flow of air in the temperate zones. Convection dominates heat transfer by air, and the amount of available space for the airflow...
01:14Mechanisms of Heat Transfer
Heat transfer between the human body and its environment occurs through four main mechanisms: conduction, convection, radiation, and evaporation.
Conduction, accounting for approximately 3% of body heat loss at rest, is the process of exchanging heat between molecules of two materials in direct contact. This can result in both heat loss and gain. For instance, when the body is submerged in water, which conducts heat 20 times more effectively than air, it can either lose or gain significant heat.
Conduction, accounting for approximately 3% of body heat loss at rest, is the process of exchanging heat between molecules of two materials in direct contact. This can result in both heat loss and gain. For instance, when the body is submerged in water, which conducts heat 20 times more effectively than air, it can either lose or gain significant heat.
01:14Mechanisms of Heat Transfer I
Just as interesting as the effects of heat transfer on a system are the methods by which the heat transfer occur. Whenever there is a temperature difference, heat transfer occurs. It may occur rapidly, such as through a cooking pan, or slowly, such as through the walls of a picnic ice box. So many processes involve heat transfer that it is hard to imagine a situation where no heat transfer occurs. Yet, every heat transfer takes place by only three methods: conduction, convection, and radiation.
02:12Enthalpy and Heat of Reaction
Combustion, commonly known as burning, is a reaction in which a substance reacts with an oxidizing agent, which in most cases is molecular oxygen, to liberate energy in the form of heat, light, or sound. The heat of combustion is also known as the enthalpy of combustion. The energy released when one mole of a substance undergoes complete combustion at constant pressure is called molar heat of combustion. Combustion reactions are exothermic; that is, they release energy, and their ΔH sign...
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Related Experiment Video
Updated: Jun 27, 2026
06:29
Simulation of Early Earth Hydrothermal Chimneys in a Thermal Gradient Environment
Published on: February 27, 2021
Impact heating and the hidden Hadean.
Tim E Johnson1, Craig O'Neill2, Simon Turner3
1Curtin Frontier Institute for Geoscience Solutions (CFIGS), School of Earth and Planetary Sciences, Curtin University, Perth, WA, Australia.
Science (New York, N.Y.)
|June 25, 2026
Summary
Early Earth
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10:52Conducting Elevated Temperature Normal and Combined Pressure-Shear Plate Impact Experiments Via a Breech-end Sabot Heater System
Published on: August 7, 2018
09:46Protocol for Measuring the Thermal Properties of a Supercooled Synthetic Sand-water-gas-methane Hydrate Sample
Published on: March 21, 2016
Area of Science:
- Geology
- Planetary Science
- Geophysics
Background:
- The composition and state of Earth's Hadean eon crust (≥4.03 billion years ago) remain poorly understood.
- Previous geodynamic models primarily focused on internal heat sources, neglecting the significant Hadean impact flux.
Purpose of the Study:
- To investigate the influence of Hadean impact heat flux on early Earth's crustal evolution.
- To determine the role of impacts in shaping the initial composition and structure of Earth's crust.
Main Methods:
- Utilized a stochastic model to simulate the Hadean impact flux.
- Integrated impact-generated heat into geodynamic models of early Earth.
Main Results:
- Time-integrated heat from impacts significantly exceeded internal heat production during the Hadean.
- Extensive melting of the Hadean crust occurred below a few kilometers depth.
- Impacts drove gravitational segregation, leading to silica-rich crustal compositions.
- Impact heating diminished significantly after 3.9 billion years ago, enabling crustal thickening.
Conclusions:
- Hadean impact events were a dominant factor in early crustal evolution, leading to molten conditions and compositional changes.
- The decline in impact activity post-3.9 billion years ago likely facilitated the formation of enduring continental crust.