Geothermal gradient

Geothermal gradient is the rate of increasing temperature with respect to increasing depth in the Earth's interior. Away from tectonic plate boundaries, it is about 25 °C per km of depth (1 °F per 70 feet of depth) near the surface in most of the world. Strictly speaking, geo-thermal necessarily refers to the Earth but the concept may be applied to other planets. A line tracing the gradient through the planetary body is called a geotherm on Earth and other terrestrial planets. On the Moon it is called a selenotherm.

The Earth's internal heat comes from a combination of residual heat from planetary accretion, heat produced through radioactive decay, and possibly heat from other sources. The major heat-producing isotopes in the Earth are potassium-40, uranium-238, uranium-235, and thorium-232. At the center of the planet, the temperature may be up to 7,000 K and the pressure could reach 360 GPa(3.6 million atm). Because much of the heat is provided by radioactive decay, scientists believe that early in Earth history, before isotopes with short half-lives had been depleted, Earth's heat production would have been much higher. Heat production was twice that of present-day at approximately 3 billion years ago, resulting in larger temperature gradients within the Earth, larger rates of mantle convection and plate tectonics, allowing the production of igneous rocks such as komatiites that are not formed anymore today.

Geothermal energy

Geothermal energy is thermal energy generated and stored in the Earth. Thermal energy is the energy that determines the temperature of matter. The geothermal energy of the Earth's crust originates from the original formation of the planet and from radioactive decay of materials (in currently uncertain but possibly roughly equal proportions). The geothermal gradient, which is the difference in temperature between the core of the planet and its surface, drives a continuous conduction of thermal energy in the form of heat from the core to the surface. The adjective geothermal originates from the Greek roots γη (ge), meaning earth, and θερμος (thermos), meaning hot.

Earth's internal heat is thermal energy generated from radioactive decay and continual heat loss from Earth's formation. Temperatures at the core–mantle boundary may reach over 4000 °C (7,200 °F). The high temperature and pressure in Earth's interior cause some rock to melt and solid mantle to behave plastically, resulting in portions of mantle convecting upward since it is lighter than the surrounding rock. Rock and water is heated in the crust, sometimes up to 370 °C (700 °F).

This Old House

This Old House is an American home improvement media brand with television shows, a magazine and a website, ThisOldHouse.com. The television series airs on the American television station Public Broadcasting Service (PBS) and follows remodeling projects of houses over a number of weeks. This Old House is produced by This Old House Ventures, Inc. with WGBH Boston as the PBS distributing station. Warner Bros. Domestic Television distributes the series to commercial television stations in syndication. Time Inc. launched This Old House magazine in 1995, focusing on home how-to, know-how and inspiration. In 2001, Time Inc. acquired the television assets from WGBH Boston and formed This Old House Ventures, Inc.

Overview

This Old House and its sister series Ask This Old House are often broadcast together as The This Old House Hour (originally known as The New This Old House Hour). Both shows are owned by This Old House Ventures, Inc. (a subsidiary of Time, Inc.) and are underwritten by GMC and The Home Depot. Weyerhauser lumber distributor, a previous underwriter, by 1989 had donated more than $1,000,000 a year to the show.This Old House is also underwritten by State Farm Insurance and Lumber Liquidators, Inc. Other underwriters throughout the show's tenure included Parks Corporation, Glidden paints, Montgomery Ward, Ace Hardware, Kohler plumbing, Schlage locks, Century 21 Real Estate, Toro lawnmowers/snowblowers, ERA Real Estate, Angie's List, and Mitsubishi Electrics. Two of the original underwriters were Weyerhauser and Owens-Corning.

Old House

Old House could refer to: