Py
- Pylon
- The tower above a bridge deck that usually carries cable stays.
- Pyramid
- In ancient Egypt, a quadrilateral masonry mass with steeply sloping sides meeting at an apex, used as a tomb.
- Pyranometer
- An instrument which measures global radiation, the combined intensity of direct solar radiation and diffuse sky radiation.
- Pyrex Glass
- A type of glass that is resistant to heat and chemical attack. Often used in cookware and in laboratory equipment.
- Pyrgeometer
- An instrument which measures the effective terrestrial radiation.
- Pyrheliometer
- An instrument which measures the intensity of direct solar radiation.
- Pyroclastic
- Fragmented rock material formed by a volcanic explosion or ejection from a volcanic vent.
- Pyroclastic Flow
- A hot, dry, fast-moving (10-100m/s) and high-density mixture of ash, pumice, rock fragments, and gas formed during explosive eruptions or from the collapse of a lava dome.
- Pyroclastic Surge
- Turbulent, low-density cloud of hot rock debris and gases that moves over the ground surface at high speed. Lower density than Pyroclastic Flow.
- Pyroelectricity
- Electric charge produced as a material undergoes a temperature change.
- Pyrolyser
- An instrument that breaks complex molecules into constituents by using heat.
- Pyrolysis
- Thermal degradation of waste in the absence of air to produce char, pyrolysis oil and syngas.
- Pyrometer
- A device for measuring the high temperatures in a furnace.
- Pyrophoric
- Catches fire spontaneously when exposed to air at normal room temperature.
- Pythagoras
- Greek philosopher and mathematician; held that numbers were basic to matter.
- Pythagoras Theorem
- The Square on the Hypotenuse is equal to the sum of the squares of the other two sides.
- Pythagorean Triangle
- A right triangle whose sides are integers.
- Pythagorean Triple
- An ordered set of three positive integers (a,b,c) such that a2+b2=c2.