Negative ions are invisible, odorless, tasteless molecules that we inhale in abundance in environments like mountains, waterfalls, and beaches. They appear in nature when air molecules split due to sunlight, radiation, and moving air and water. Once in our bloodstream, negative ions are believed to produce biochemical reactions that increase levels of serotonin (the mood chemical), helping to alleviate depression, relieve stress, and boost daytime energy levels.
Fog is a compact cloud of minuscule water droplets suspended in the atmosphere near the earth’s surface. If visibility is restricted to 1km or less, it is considered ‘fog’. If visibility is greater than 1km, it is called ‘mist’. Atmospheric pollutants can intensify fog and turn it into ‘smog’, a portmanteau of the words ‘smoke’ and ‘fog’.
Snow is atmospheric water vapor frozen into ice crystals. Although these crystals/snowflakes typically display a six-sided symmetrical shape, each one is unique in structure. You might expect snow to appear transparent since it is made out of water. However, snow has so many light-reflecting surfaces (myriad snowflakes) that it splits the light into all of its colors (frequencies), which then blend together to give snow its pristine white color.
An altimeter used in conjunction with a topographic map can help verify location and aid navigation. A barometric altimeter can be more reliable and more accurate than a GPS receiver for measuring altitude. GPS altimeters may have difficulty in finding a signal, e.g. in a deep canyon or beside a steep cliff, and may give inaccurate measurements if available satellites are near the horizon and line of sight is blocked.
Air pressure is caused by the gases in the atmosphere – mainly nitrogen (N2) and oxygen (O2) – pushing in all directions (think of gas in a balloon). These gases may be relatively light, but there are a lot of them in the atmosphere stretching approximately 24 kilometres (15 miles) above our heads. Air density/pressure varies due to: temperature – hotter air is less dense so floats above cool air; altitude: the closer air is to the planet’s surface – the more gravity packs its molecules together so increases its density; and humidity.
Paradoxically water vapour molecules H2O – two hydrogen (lightest matter in the universe) plus one oxygen – are actually lighter than air molecules, which are approximately 80% N2 (two nitrogen atoms) and 20% O2 (two oxygen atoms). That’s one – though not the only one – of the reasons clouds float! Note that liquid water is much heavier than water vapour, which is why it rains.
Because of the earth’s rotation, angle, sun striking half the surface, oceans and ice caps, the air temperature – and air pressure – varies throughout the day, the seasons and the years. These variations cause colder and hotter regions in the atmosphere. Colder regions are denser than warmer regions so have higher pressure. High pressure moves towards low pressure (prick a balloon and the gas rushes out, not in) causing wind. Wind moving from high pressure to low pressure are between a rock (earth’s surface) and a hard (high-pressure) place, so there is nowhere for all that incoming air to go. Nowhere to go… except UP!
When the air pressure drops very low, massive amounts of air are forced upwards so fast that they spin to form whirlwinds, tornadoes, cyclones and hurricanes. Note that cyclones and hurricanes are similar phenomenon but spin in different directions due to the Coriolis effect: cyclones rotate anti-clockwise in the southern hemisphere, hurricanes clockwise in the north.
However, while the Coriolis effect influences light air over thousands of kilometers, despite widespread belief it is far too weak to influence the direction small amounts of relatively heavy water spin down the plughole. That’s just an urban myth!
So in areas of relatively low pressure, air generally rises up. And as it rises, the air cools and the molecules of water it contains condense into water vapour that eventually forms white fluffy clouds. However, if the air pressure is low enough, the winds will be stronger so the incoming air will rise even higher where the lower temperature of the air can no longer support the ever denser water molecules, so they precipitate into rain, snow or even freeze as hail.
But predicting the weather isn’t quite that simple because it isn’t the actual air pressure that forecasts the weather – knowing the air pressure just tells you what you can learn by looking out the window, i.e. what the weather is now, not what’s coming. It is the change in air pressure that indicates what weather is coming, rather than the actual pressure itself.
The World Land Speed Record of 1,228 km/h (763 mph) was set by the team Thrust SSC of Richard Noble, driver Andy Green, on 15th October 1997 at Black Rock Desert, Nevada (USA) and became the first land vehicle to officially break the sound barrier. Thrust SSC has the power of 1000 Ford Escorts, or 145 Formula One cars, it weighs 10 tonnes, and performance estimates it will accelerate from standstill to 161 km/h (100mph) in four seconds.
The World Fastest Sailboat, the Vestas Sailrocket 2 exceeded 65,45 knots/500 m (120 km/h or 75 mph) on November 24, 2012 in Walvis Bay, Namibia held by Paul Larsen. The 40-foot, British-built craft weighs just over 600 pounds but skims along the water on hydrofoils. It was built from carbon fiber with a core of Nomex Honeycomb, a composite material and titanium.
The Eurocopter X3 has opened the frontiers of aviation by setting an unofficial speed record for a helicopter of 472.26 km/h (293.29 mph) in level flight on June 7, 2013. Eurocopter achieved the historic 255-knot speed milestone with the X3 flying at an altitude of around 10,000 feet during a 40 minute test flight.
During the return from the moon on May 26, 1969, the Apollo 10 crew achieved the fastest speed of a manned vehicle by traveling at 24,790 mph (39,896 km/h) relative to earth. The crew members were Thomas Stafford, John W. Young and Eugene Cernan, and it was the first space mission to include an all veteran crew.