The late professor Stephen Hawking's final theory on the origin of the universe has been published today in the Journal of High Energy Physics. Hawking collaborated with Professor Thomas Hertog from KU Leuven on the paper which was submitted for publishing before Hawking's death in March this year.
The paper’s ideas are based on string theory, it predicts the universe is finite and that the universe's origin may, in fact, be far more simple than current theories relating to the Big Bang. Modern Big Bang theorists believe that the universe came into existence with a burst of inflation that started to occur just moments after the Big Bang itself.
It is thought that once this inflation begins the quantum effects can keep it going indefinitely. The part of the universe that we can observe is just a hospitable pocket where inflation has ended.
"The usual theory of eternal inflation predicts that globally our universe is like an infinite fractal, with a mosaic of different pocket universes, separated by an inflating ocean," said Hawking in an interview last autumn. "The local laws of physics and chemistry can differ from one pocket universe to another, which together would form a multiverse.
But I have never been a fan of the multiverse. If the scale of different universes in the multiverse is large or infinite the theory can't be tested." In their new paper, Hawking and Hertog say the eternal inflation model is wrong.
This is because Einstein's theory of general relativity breaks down on quantum scales. "The problem with the usual account of eternal inflation is that it assumes an existing background universe that evolves according to Einstein's theory of general relativity and treats the quantum effects as small fluctuations around this," said Hertog.
"However, the dynamics of eternal inflation wipes out the separation between classical and quantum physics. As a consequence, Einstein's theory breaks down in eternal inflation."
"We predict that our universe, on the largest scales, is reasonably smooth and globally finite. So it is not a fractal structure," said Hawking. Their latest research doesn’t disprove multiverses, but reduces them to a much smaller range.
This means the multiverse theory will be able to be tested by a larger range of physicists in the future.
Professor Hertog whose work has been supported by the European Research Council, already has plans to test it by looking for gravitational waves that could have been generated by eternal inflation.
Hertog first announced the new theory at a conference at the University of Cambridge in July of last year, organized on the occasion of Professor Hawking's 75th birthday.
The 20th century saw an increasing use of technology in the chair construction with such things as all-metal folding chairs, metal-legged chairs, the slumber chair, moulded plastic chair and ergonomic chairs.
Because of its used for various purposes, there are three (3) factors to consider when choosing an executive chair.
FORMS
Office chairs comes in several styles and forms to suit almost every need. The executive office chair which is more expensive than a basic chair features a more luxurious design and materials,its unique adjustable options for the whole body allows for more tailored comfort. Mostly its constructed with thickened padding for higher comfortability.
There's also task office chair which features a frame made from steel or plastic and typically includes arm rests and back support. The seat and back rest are upholstered with fabric to enhance comfort. The other forms are the swivel office chair which features controls that adjusts the height and the ergonomic chairs which reduces tension in the body, predominately in the back and the hips. It features an adjustable seat, arm and back height, as well as lumber support.
FEATURES
Features that are to be considered are as follows
Upholstery : office chairs come upholstered in a variety of materials and in different colours. The chair produced with Leather are usually more expensive.
Adjustable controls: look for a chair that offers controls for height, depth, tilt and arm rest, to enable adjusting of the chair to suit your needs for better comfort and body alignment.
Lumbar support: To reduce stress and strain on our back.
FUNCTIONS
Functions and comfort are very important when choosing an executive chair:
Cushioned seats: cushioning and paddling provides a contoured seat that can alleviate pressure associated with prolonged sitting.
Durability: The rate at which the chair would be used should and where it will be used should be consider. Factors for conference rooms differs from that an office.
Size: choose an office chair that suits your height and weight for proper support and comfort. If you have more weight or taller, a big and tall chair is designed with a generous seating area and higher adjustment.
Style: When choosing an office chair , the décor should be considered, also the arm style, upholstery material and base style to determine what best compliment your space.
Note: A great office chair can make a difference in getting through a long work day with ease and increased output efficiency.
Machines tends to fail or work below its required strength or capacity due to improper lubrication of the machine components. Many operators ignores the fact that friction exist thereby underestimating the importance of lubrication. Some do not know what lubrication means, its principle,the positives and negatives and why its necessary for it to be in check.
The techniques of using lubricants to reduce friction between surfaces is termed lubrication. This definition contains two main terms, lubricant and friction.
Understanding what friction is, will help us in the application of lubricants.
Friction is that which hinders a body from moving smoothly on the surface of another, a stationery and a moving part or two or moving parts. Friction has a role to play in machines but when it becomes excessive or when its not needed, damage will occur in the machine or its component. Effects like corrosion, overheating, wear and others have the possibility of occurring if its not lubricated.
To achieve reduced friction the lubricant which is the applied element must meet the following purposes.
It most be able to resist temperature at the extremes(freeze & boiling point) to retains its viscosity index.
The lubricant must be thick enough to seal and thin enough to minimize fluid friction
Forming a sliding seal between the moving surface
Cleaning function between the moving surface.
It must not have a vanish tendency
Lubricant are of various types and functions
Engine oil: lubricates the engine moving parts
Grease: used for bearings
Hydraulic oil: used for power steering of vehicles, excavators, industrial machineries etc.
Brake fluid: used in hydraulic brake and clutches
Transformer oil: used in oil filled transformers
Soluble oil: used in vehicles to regulate the boiling and freezing point of water
Solid lubricant(graphite)
WHAT IF I DO NOT LUBRICATE
Inadequate lubrication often produces excessive heat thus bearing failure and the heat build up lowers the viscosity of the lubricant. The thickness of the fluid film that separates the bearing surfaces might be reduced which may lead to metal to metal contact and bearing failure.
In internal combustion engines, lacks of lubrication causes metal to metal contact of the piston and the cylinder wall, improper sitting of the piston rings, over heating of valves,the connecting rod, cylinder head, cylinder wall, piston etc and as a result of this denotation occurs.
Note, proper lubrication enhances the life span of your bearings and machines, thus increased output efficiency. Time, money and manpower will be saved when proper lubrication are done.
Plants are device that make work easier and faster, they consist of several components coupled for the effectuation of power supply.
Plants generally are classified as
Domestic plants
Industrial plants
For the purpose of the topic, its classifications won't be explained,comment to inform me if you need it
Simple steps in engine or plant servicing
Warm the engine to reduce viscosity ie thickness of the lubricant
Remove the battery terminals
Drain the oil
Remove the oil filter (using filter clamp)
Filter clamp
Apply new oil filter and oil
Oil filter
Change fuel filter
Fuel filter
Bleed the engine ( slacking the nuts of the injector nozzle) then cranking the engine
For carburetors bleeding is not necessary
Apply new engine oil and gauge
N:B over gauging of oil weakens the rings of the piston
Change the oil filter if its blocked
In addition to start an engine the followings are compulsory
Check oil gauge
Check water level
Check gasoline level
Prime the engine
I know you have gotten the trick and knowledge immensely impacted... Good luck
Just in case you think the two stroke cycle engine will become obsolete, I advice you have a rethink because it will never be. The two stroke cycle engine is a type of internal combustion engine(I.C.E) that was developed to obtain high power output from a simple engine size and valve design via the movement of the piston during one crankshaft revolution. It works in spark ignition and combustion ignition engine. The general principle in which engines operate is based on
Induction
Compression
Power or expansion
Exhaust
However the two stroke cycle engine uses port(inlet port, transfer port and exhaust port) instead of valve to carryout the induction and exhaust operations. In every 360° rev, one cycle is completed i.e in every 180° rev, two strokes(exhaust and induction) followed by the compression and power stroke to complete the cycle.
In the two stroke cycle the charge is introduced through the inlet port from the carburetor into the crankcase to generate partial pressure on the charge, when the piston is at TDC . The downward movement of the piston causes the partially compressed charge to move into the cylinder through the transfer port. The compression stroke follows immediately to ignite the charge when the piston moves upward thereafter the power stroke causing the exhaust port to open for scavenging.
For the same size of flywheel the two stroke cycle engine runs smoother.
Theoretically the two stroke produces double the useful power to that of a four stroke engine with the same cylinder capacity
lubrication of oil and fuel mixture can be done with the ratio of 1:16 and 1:24
Less maintenance
Though they are not used for automobile due to mixed oil and fuel, over heating under heavy driving conditions and other factors but they are as important as the four stroke engine.
Mechanical engineering is a very wide discipline that, effectively, covers anything that moves. Its breadth is due, in part, from its need to cover the design and manufacture of anything and everything in a moving system.
This ranges from a system's smallest components to the completed, sometimes enormous, machine as a whole. Throughout history some innovations have come to define mechanics as we know it today, the following are no exception.
These engineering innovations range from the any one of the classical 'simple machine' to complex concepts such as flight. This list is far from exhaustive and in no particular order.
1. The Aeolipile Was an Early Steam Reaction Turbine
The Aeolipilewas the world's first rotating steam engine or more technically correct, a steam reaction turbine. It was devised by the great Heron of Alexandria in the 1st Century AD and described it in great detail in his book Pneumatica.
This relatively simple device works by heating a reservoir of water within the device to generating steam. The steam is then conducted through one of the copper supports to a pivoted brass sphere.
Once the steam reaches the sphere it escapes through one of two nozzles at the ends of two, small, opposingly pointing arms. The escaping steam generates thrust and causes the sphere to rotate.
The basic principle is simple but the device’s real genius is its bearings. Only one of the supported arms pass steam to the sphere (via a sleeve bearing).
This pushes the sphere against the other supporting ‘solid’ arm that also has a thrust bearing. The solid arm comprises of a conical point that bears against a matching indentation on the surface of the sphere. This combination holds the sphere in place whilst it rotates.
There are very few innovations in mechanical engineering that have had as much influence as the wheel. The modern world would look very different without them.
Wheels, technically the wheel and axle is one of the six simple machines as defined in antiquity and expanded during the Renaissance.
The first depictions of wheeled-vehicles appear on an earthenware Bronocice pot from Poland and dates to around 4000 BC. The pot clearly depicts a wagon of some kind with four wheels set on two axles.
The earliest actual evidence of a physical wheel-axle combination comes from Slovenia and is dated to around 3360-3030 BC.
Wheels literally changed the world and have been a constant feature of human transport devices the world over.
Windmills are incredibly ingenious devices that are able to convert wind power into useful mechanical work. This is achieved by using large ‘sails’, usually made of wood, imparts rotational force to the main shaft that in turn can be used to power a process, like grinding flour.
The Persians were some of the first people to harness the power of wind when they began building early forms of windmills in Iran and Afghanistan in around the 7th Century AD.
These early windmills consisted of sails radiating from a vertical axis within a building with two large openings for the inlet and outlet of wind diametrically opposite each other. The mills were used to directly drive single pairs of millstones without the use of gears.
They were one of the first means by which civilizations were able to directly replace human beings as the main source of power for a process.
Windmills would become increasingly widespread throughout Europe during the Middle Ages and stayed in use well into the 19th Century.
The development of steam power during the industrial revolution would spark the eventual decline of windmills.
Pulleys are one, or several wheels, on an axle or shaft that support the movement and a change of direction of a cable or belt (that is usually taut). They transfer power between the shaft and cable and provide an immense mechanical advantage for providing large forces ideal for lifting heavy objects.
Pulleys come in various types:-
- A fixed pulley has an axle mounted in bearings attached to a supporting structure
- Movable pulleys have axles mounted on movable blocks.
- Compound pulleys are a mixture of the above two. The perfect example is the block and tackle pulley system.
The pulley was identified by the great Heron of Alexandria as one of the six simple machines. Today pulleys are an integral part of many mechanical systems including fan belts, flag poles, and water wells.
Long before the Wright Brothers were even born, man has been trying to take to the air. One such lesser-known flight pioneer was Brother Eilmer. Eilmer was a monk from Malmesbury Abbey, England when he made an early attempt at flying in 1010 AD.
An account of the event can still be found in William of Malmesbury’s book Gesta Regum Angloru
It is said that he was inspired by the legend of Icarus to build a basic glider and attempt to fly. His glider was built from a wooden frame and either linen or parchment.
He would later launch himself from about 18 meters above ground level, glided 200 meters and subsequently panicked and crashed, breaking both his legs.
He returned to the drawing board and planned his next flight only to halted by an embargo from his Abbot to stop any further attempts.
Brother Eilmer’s desire to fly, and others that followed him, like the Ottoman Celebi to the great Leonardo da Vinci, would drive our understanding of flight and aerodynamics.
6. Steel
Steelhas been known about since the beginning of the Iron Age. But for most of this time, the quality of iron produced varied widely.
The first blast furnaces began appearing in China in around the 6th Century BC and would spread into Europe during the Middle Ages. By the 17th Century iron was, more or less, well understood and by the 19th Century production methods and quality were improved dramatically.
Early metallurgists realized that when iron gets very hot it begins to absorb carbon. This, in turn, reduces the melting point of iron as a whole and makes the final product brittle.
They soon realized that they needed to find a way of removing high carbon contents to make iron products less brittle.
In around 1050 AD the precursor to the modern Bessemer Process is developed. This process decarbonized the metal through repeated forging under a cold blast.
Although this process was far less efficient that Bessemer’s later development it would form one critical stage in the development of our knowledge of the metallurgy of iron and steel.
The most important development was made by Henry Bessemer in 1856. He managed to find a way of using oxygen to reduce the carbon content in steel, thus creating the modern steel industry.
7. Sailed Ships Opened Up the Oceans
The very first depiction of a sailed ship dates back to around 3300 BC in an Egyptian painting. These early boats featured a square sail as well as banks of oars.
As they were confined to the Nile River and depended on winds within the narrow channel it was vital to retain oars during times of insufficient wind speed.
This combination dominated early ships for centuries reaching heights in technological advancements with the triremes of the classical period.
The first sails were probably made of animal skins but these were replaced by woven reed mats and eventually cloth in predynastic Egypt.
Later, sails were made of woven flax fiber in Europe which is still used today though cotton has largely replaced it.
Sailed ships would enable mass exploration of the seas and open up new trade routes. They would, in effect, shrink the world and allow previously disconnect nations to exchange goods and knowledge.
They would also enable nations to expand their influence around the world and, in some cases, become the workhorses of empire.
Incentives like these would further drive advancement in ship technology and mechanical engineering to the present day.
The printing press was one of the most important inventions for mechanical engineering and the population at large. Johannes Gutenberg’s machine was groundbreaking in its own time and set the stage for enormous advancements made during the Renaissance and Industrial Revolution.
Movable type printing had been around for some time before Gutenberg, notably in China, but his device was the first to mechanize the process of applying text and images to paper en masse.
Gutenberg’s press was modeled on the ancient wine presses of the Mediterranean and in fact, was made from a modified wine press. It was also developed on the existing presses of the medieval period.
His press worked by rolling ink over a pre-arranged raised surface of movable text held within a wooden frame. This was then pressed against a sheet of paper to create a copy.
This process was vastly more efficient than other presses of the time not to mention the previous process of hand copying books.
The press would allow books to be produced more quickly, and, most importantly, cheaper, enabling more and more people to afford to buy them. This would mark a watershed in human and engineering history.
The invention of the pistonis widely credited to French physicist, Denis Papin in 1690 AD. His design for a steam piston engine was built upon by later inventors like Thomas Newcomen and James Watt during the 18th Century.
Its invention, along with other advancements in steam engine technology, would mark the ‘true’ beginning of the industrial revolution.
Pistons tend to be contained within a cylinder that is made air-tight by use of piston rings. In modern engines, the piston serves to transfer force from expanding gas in the cylinder into reciprocating motion on a crankshaft.
This process is effectively reversed when applied to pumps.
Today pistons are essential components in many reciprocating engines, pumps, compressors and other similar devices.
"Give me a place to stand, and I shall move the Earth with it' is a remark of Archimedes who formally stated the correct mathematical principle of levers" - Pappus of Alexandria.
The lever, yet another simple engine, consists of a beam (or rigid rod) pivoted on a fixed hinge or fulcrum. Levers are incredibly useful devices that can be used to provide mechanical advantage to move very heavy objects with relatively little effort, otherwise known as leverage.
Depending on where the fulcrum is located as well as the load and effort, levers can be divided into three types:-
- Class 1 levers are those where the fulcrum is located in the center of the beam. Examples include a seesaw or a crowbar.
- Class 2 levers are those where the load (resistance) is located in the middle. Examples include a wheelbarrow or brake pedal.
- Class 3 levers are those where the effort is located in the middle. Examples include tweezers or even your own jaw.
Levers are first identified in the works of Archimedes in the 3rd Century BC,
11. The Locomotive Revolutionized Transportation Forever
Richard Trevithick, in 1801-1804 built both the first steam carriage and an experimental steam locomotive in Pen-y-Darren, Wales, UK. He later sold the patent and in 1804 revised his original version to successfully carry 10 tons of iron, 5 wagons, 70 men for about 10 miles.
This trip took just over 4 hours meaning his locomotive clocked up an eye-watering 2.4 miles per hour. This made it the very first steam locomotive to produce actual practical work.
The locomotive would go on to literally transform the face of industry and transportation the world over.
The humble yet immensely important ramp, or inclined plane, is another of the fundamental six simple machines that allows heavy loads to be moved vertically with relatively little effort. They are widely used in many applications from loading goods into trucks to disabled access ramps.
Moving an object up an inclined plane requires less force than lifting it straight up at a cost of an increase in the distance moved. The mechanical advantage for ramps is equal to the ratio of the length of the sloped surface to the height it rises.
The screw and wedge are other simple machines that can be considered variations on the inclined plane or ramp rather than discrete forms.
Gears or cogwheels are integral components of any rotating machine that allow for the change in speed, torque or direction of any power source. They are one of the fundamental mechanical engineering innovations in history.
Any change in torque with the use of gears and cogwheels necessarily creates a mechanical advantage thanks to the phenomenon of the gear ratio.
A gear can mesh with a linear toothed part, called a rack, producing translation instead of rotation.
It is unclear exactly when gears and cogwheels were first invented but some credit Archimedes. Today, gears are present in many moving systems and machines from bicycles to ship engines.
The bearing is another fundamental machine element that has come to define mechanical engineering. These devices allow the constraint of relative motion in one direction or plane whilst simultaneously reducing friction between moving parts.
Bearings come in many shapes and sizes and range from components holding shafts or axles in place (plain bearing) to more complex systems like ball bearings.
Modern-day sophisticated bearings often demand the highest level of precision and quality in manufacturing.
15. The Wedge Is Great For Breaking Things
The wedge is another simple machine and fundamental innovation in mechanical engineering. They have been used since prehistorical times for activities like splitting logs (axes) or rocks (chisels).
Wedges are defined as movable inclined planes that can be used to separate two objects (or portions thereof), lifting objects or holding them in place via the application of force to the wide end. The wedge's shape, therefore, converts one input force into perpendicular forces 90 degrees to the inclined surfaces.
The mechanical advantage achieved by any wedge is dependent on the ratio of its length to thickness. In other words wide, short wedges require more force but produce a quicker result than a long, low angled wedge.
16. Electrical Motors Convert Electricity Into Motion
Motors are electronic machines that convert AC or DC electrical current into rotational movement. Most common electrical motors work through the interaction of a magnetic field and winding currents to generate a force.
The basic principle behind electric motors, Ampere's Force Law, was first described by Ampere in 1820 and was first demonstrated by Michael Faraday in 1821. One of the first practical motors was created by Hungarian physicist, Anyos Jedlik in 1828.
Motors are found in many applications around the world from industrial fans to power tools to computer disk drive.
Weather forecast instruments are a vital component in our application of science and technology in an attempt to predict future conditions of the atmosphere for a given time and location. This article will help you know the basic weather forecast instruments and invention which aids scientist in reading the weather today.
1. The Barometer: Weighing the Air Since the 1600's
The barometer is one of the most important instruments in weather forecasting. It is used, as the name suggests, to measure localized atmospheric air pressure.
Evangelista Torricelli is widely credited with the invention of the barometer in the mid 17th Century. But historical documentation also indicates that Gasparo Berti, another Italian scientist, built a working barometer by accident between 1640 and 1643.
Berti was a friend of Galileo who in turn was the mentor of Torricelli. Berti could not explain how his 'barometer' worked, invoking a theory that the vacuum in some way held the water level in the tube and asked Galileo for advice.
If this is true, Torricelli later made the connection between atmospheric pressure and phenomenon described by Gasparo Berti in his apparatus.
He would later write:-
"We live submerged at the bottom of an ocean of elementary air, which is known by incontestable experiments to have weight".
Torricelli also later discovered he could replicate the phenomenon in 'miniature' using denser fluids like mercury.
Traditionally, barometers came forms such as:
- Water (Goethe)
- Mercury and
- Aneroid (later invented in 1844 by Lucien Vidi).
Analog forms are rarely used for official weather prediction today, having largely been replaced with digital ones. Digital barometers use electrical transponders, instead of liquids in a vacuum, to detect atmospheric pressure and are the most widely used form in official weather stations today.
Air pressure, when combined with wind observations has been used to predict, fairly accurately, short-term weather forecasts since the later 19th Century.
Wind speeds can be accurately measured using devices called anemometers. They were first developed by Italian artist Leon Battista Alberti in 1450 but were perfected much later in the 20th Century.
They are a common instrument often found on weather stations. Their design has changed very little since the 15th Century.
The most easily recognizable forms used in weather forecasting include:-
- Cup anemometers.
- Vane anemometers.
The first determines wind speed based on how fast the cup wheel spins. Improvements made to the design in 1991 by Derek Weston, also allows them to determine wind directions from the cyclical changes in cup wheel speed.
Although simple in theory, other factors need to be factored in before determining true wind speeds. For instance, turbulence from the device itself and friction from the mount point need to be accounted for.
A vane anemometer, on the other hand, combines a propeller and a tail on the same axis to obtain accurate and precise wind speed and direction measurements from the same instrument. Wind speed is determined using a rev counter which is then converted to wind speed.
There are also other forms of anemometer ranging from hot-wire anemometers (the most popular constant-temperature devices), Laser Doppler anemometers, ultrasonic anemometers and ping-pong ball anemometers (though generally confined to middle-school experiments).
Today, radar forms an integral part of any weather instrumentation and is used, primarily, to locate precipitation, track it and estimate its type (snow, rain etc) and intensity. Radar can also be used to forecast precipitation associated with thunderstorms, hurricanes and winter storms.
Radar was initially developed during the Second World War as a means of detecting and tracking enemy aircraft. Personel soon noticed "noise" or "echoes" on their displays from precipitation which revealed a potential peacetime application for the technology.
Shortly after the conclusion of the war, surplus radar equipment was repurposed on weather stations.
Modern stations use pulse-Doppler Radar that is actually capable of detecting the motion of rain droplets as well as the intensity of the precipitation. They typically use dual-polarization radar that sends and receives vertical and horizontal pulses.
This gives meteorologists a much clearer appreciation of the multi-dimensional situation at any one time.
4. Rain Gauges Have Been Used to Measure Rain Since 500 BC
Rain gauges are pretty simple instruments used to directly measure the amount of liquid precipitation in one location over a period of time. They are vital instruments for meteorologists and hydrologists alike.
Rain gauges are one of the world's oldest and most basic weather instruments around. Some of the first recorded apparatus dates back to Ancient Greece around 500 BC. Other records indicate that people living in India also started measuring rainfall in around 400 BC.
The first standardized rain gauge appears to have been developed in 1441 AD in the Joseon Dynasty of Korea. The first 'tipping bucket' form of rain gauge was developed by Sir Christopher Wren in 1662.
Richard Towneley is the first person to systematically measure and record rainfall over a period of 15 years from 1677 to 1694. He later inspired other scientists of the age to follow suit, eventually leading the pioneering work of George James Symons (one of the first official Meteorologists who founded the British Rainfall Organisation).
Most modern rain gauges generally measure the precipitation in millimeters in height collected on each square meter during a certain period, equivalent to liters per square meter.
This can be simple collection systems that are later visited by meteorologists to assess rainfall or automated to gather data in situ.
5. Weather Balloons Take Weather Forecasting to New Heights
Weather or sounding balloons are effectively mobile weAather stations that carry scientific instruments into the upper atmosphere. They tend to be equipped with suites of sensors to measure weather variables like atmospheric pressure, temperature, and humidity.
This information is relayed to ground-based receiver stations to be stored and analyzed.
Other information, like wind data, can be obtained by tracking the balloon's position using radar, radio direction finding or installing GPS systems on each balloon. Other instruments are encased in small, parachute-equipped though often expendable, payloads called radiosondes.
Each balloon tends to comprise a large, often up to 6 ft (1.8 meters) wide, helium or hydrogen filled latex balloon. The balloons then carry an instrument payload package that encases and protects the more sensitive instruments during its flight.
Leon Teisserence de Bort, a French meteorologist, was one of the first people to use weather balloons. He launched hundreds of them during 1896 which led to his discovery of the troposphere and stratosphere.
Some balloons, called transosonde, are designed to stay aloft for long periods of time. They were initially devised to help monitor radioactive debris from atomic fallout during the 1950's.
Hygrometers are tools used to measure humidity or air moisture content in the atmosphere, soil or indoors. The very first, though crude, hygrometer was invented by the Italian genius Leonarda da Vinci in around 1480.
More modern versions were created by Swiss polymath Johann Heinrich Lambert in 1755.
Older analog hygrometers come in various forms including hair tension hygrometers and sling psychrometers to name but a few. The former, as the name suggests, use animal hair (which is hygroscopic - water absorbing) to 'detect' changes in relative air humidity as the hairs length changes.
The latter uses a set of two thermometers, one moistened and one dry, that are spun in the air. As temperatures fluctuate above or below the freezing point of water, the 'wet' thermometer will either show a cooler temperature (if water evaporates above freezing point) or lower (if ice forms) when compared to the dry thermometer.
Modern hygrometers tend to be digital versions as they are more reliable and accurate. They use electronic sensors to detect changes in relative humidity and convert it to an easily readable numerical value.
One of the newer 'kids on the block' weather satellites are the highest tech options available to weather forecasters. They are able to view and gather large amounts of data about the Earth's weather and climate with unparalleled views.
They tend to hold either asynchronous orbits (therefore covering the entire Earth's surface) or geostationary (thereby focussing on a single spot for extended periods). As early as 1946 ambitions to put cameras into space was already being developed.
The first weather satellite, Vanguard 2, reached Earth's orbit in February 1959. This sparked the beginning of a proliferation of weather satellite launches over the next 5 decades.
From orbit, they are privy to unobstructed views of the Earth's cloud systems and are able to gather information on anything from ocean temperatures to spotting wildfires or sandstorms.
Weather satellites are unique in that they are able to offer meteorologists views of weather systems over large-scale areas offering the ability to observe weather patterns hours or days before more conventional systems like weather radar.
They are often employed to track and monitor large-scale weather patterns like hurricanes and El Nino.
Pyranometers are a special type of weather forecast equipment used to measure solar irradiance on a given planar surface. They are also designed to detect and record solar radiation flux density (W/m2) within a wavelength range of 0.3 to 2.8 micrometers.
They have become the World Meteorological Organization's standard instrument and are covered under the International ISO 9060 standard. Such devices tend to be calibrated using the World Radiometric Reference which is maintained by the World Radiation Center in Switzerland.
Pyranometers tend to comprise of following main components:
- A thermopile, which is a sensor made of thermocouples in series and coated with a solar absorbing material.
- A glass dome to restrict the wavelengths of light able to enter the device. It also shields the thermopile from wind, rain, and convection
- An Occulting disc which measures the diffuse radiation and blocks beam radiation from the surface
These devices are normally passive and do not require any power supply at all. Modern electronic pyranometers, on the other hand, do require a small amount of electrical input.
Disdrometers are weather forecasting instruments that are used to measure the drop size distribution and velocity of raindrops (hydrometeors in the meteorological parlance).
Disdrometers come in various forms:
- Impact Disdrometers which directly measure the kinetic energy of raindrops,
- Acoustic Disdrometers that use piezoelectric sensors and diaphragms to determine raindrop kinetic energy and;
- Optical Disdrometers that use light to measure raindrops in a non-intrusive manner.
More sophisticated instruments are even able to distinguish between hailstones, raindrops, and graupel.
They tend to be used in various applications from traffic control to scientific studies to hydrology. Modern instruments employ microwave and/or laser technology as well as a 2D video that can be used to analyze snowflakes.
10. Transmissometer Help Determine Local Visibility
Transmissometers are weather forecast instruments used to measure the extinction coefficient of the atmosphere and seawater and by proxy estimate the visibility.
These instruments send narrow beams of energy, usually a laser, through the air towards a corresponding receiver a set distance away. Any photons that are absorbed or scattered by the air between the detector and sources will not reach the detector.
By determining the path transmission and extinction coefficient the local visibility can be determined.
These devices are also known as telephotometers, transmittance meters, or haze meters.
Ceilometers are devices that use lasers or other light sources to determine the height of clouds or cloud bases, it can also be used to determine cloud thickness. They also have applications for determining aerosol concentrations and volcanic ash in the atmosphere.
They come in two general forms:
- Optical drum ceilometers use triangulation to determine cloud height from a spot of light projected onto the base of clouds. These tend to consist of a rotating projector, detector, and recorder.
- Laser ceilometers consist of a vertically aligned laser and lidar receiver within the same location. The time taken for the reflected light to return the lidar receiver enables the device to determine cloud cover height. This technology can also be prone to false positives because it can be affected by any form or particulate matter in the air (dust, rain, smoke etc).
Ceilometers have also been shown to be fatal to birds as they get disoriented by the light beams emitted from them.
In the worst recorded ceilometer, non-laser light beam incident, approximately 50,000 birds from 53 different species died at Warner Robins Air Force Base in the United States during one night in 1954.
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