Volcanic ash consists of fragments of pulverized rock, minerals and volcanic glass, created during volcanic eruptions, less than 2 mm (0.079 inches) in diameter. The term volcanic ash is also often loosely used to refer to all explosive eruption products (correctly referred to as tephra), including particles larger than 2mm. Volcanic ash is formed during explosive volcanic eruptions when dissolved gases in magma expand and escape violently into the atmosphere. The force of the escaping gas shatters the magma and propels it into the atmosphere where it solidifies into fragments of volcanic rock and glass. Ash is also produced when magma comes into contact with water during phreatomagmatic eruptions, causing the water to explosively flash to steam leading to shattering of magma. Once in the air, ash is transported by wind up to thousands of kilometers away.
Due to its wide dispersal, ash can have a number of impacts on society, including: human and animal health; disruption to aviation; disruption to critical infrastructure (e.g., electric power supply systems, telecommunications, water and waste-water networks, transportation); primary industries (e.g., agriculture); buildings and structures.
A disaster is a natural or man-made (or technological) hazard resulting in an event of substantial extent causing significant physical damage or destruction, loss of life, or drastic change to the environment. A disaster can be ostensively defined as any tragic event stemming from events such as earthquakes, floods, catastrophic accidents, fires, or explosions. It is a phenomenon that can cause damage to life and property and destroy the economic, social and cultural life of people.
In contemporary academia, disasters are seen as the consequence of inappropriately managed risk. These risks are the product of a combination of both hazard/s and vulnerability. Hazards that strike in areas with low vulnerability will never become disasters, as is the case in uninhabited regions.
Car glass includes windscreens, side and rear windows, and glass panel roofs on a vehicle. Side windows can be either fixed or be raised and lowered by depressing a button (power window) or switch or using a hand-turned crank. The power moonroof, a transparent, retractable sunroof, may be considered as an extension of the power window concept. Some vehicles include sun blinds for rear and rear side windows. The window shield of a car is appropriate for safety and protection of debri in the road. It also comforts the driver as well. The majority of car glass is held in place by glass run channels, which also serve to contain any fragments of glass if the glass breaks.
Nowadays]when?[ some cars use composite material instead of glass.