Distance of Lighting Strike

A thunderstorm is approaching, and suddenly you hear an absolutely deafening clap of thunder. At times it becomes frightening! But how close is the lightning, really?

It is difficult to determine the distance of a lightning bolt just by looking at it, and the volume of the thunder isn’t a good way to tell either. Here's a potentially life-saving method you can use to approximate how far away lightning is.

Approximation

If we consider the atmosphere on a standard day at sea level, the speed of sound is about 330~340 m/s. Light travels in vacuum and space at approximately 299 792 458 m/s. We can use this knowledge to approximately determine how far away a lightning strike has occurred.

• Watch the sky for a flash of lightning.
• Count the number of seconds until you hear thunder.
• Divide the number of seconds by 3 (distance in kilometers).

We see the flash immediately as it happens. The speed of sound is more or less 1km per 3 seconds. If the thunder can be heard after T seconds, we can approximate the lightning strike was D ≈ T/3

Dependence on weather conditions

The speed of sound is variable and depends on the properties of the substance through of which the wave is traveling.

Sound travels through air at slightly different speeds depending on air temperature, relative humidity, altitude, pressure, wind conditions, etc. However, the difference is fairly small and won’t substantially affect your calculations.

Points to note:

• The speed of sound in dry air at 0 degrees C is about 330 m/s
• Water vapor in the air increases this speed slightly.
• Sound travels faster through warm air than through cold air.

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Top Air-filtering House Plants

Feeling lethargic lately? Is the air to stuffy in your room? Want to save money on air-conditioning bills? Well then, just get yourselves some potted plants for your home's interior.



The people over at NASA has found that living indoor plants are so efficient at absorbing contaminants in the air, that some of them will be launched into space as part of the life support system aboard future space stations.

Common indoor plants may provide a valuable resource in the fight against rising levels of air pollution. Those plants in your office or home are not only decorative, but NASA scientists are finding them to be surprisingly useful in absorbing potentially harmful gases and cleaning the air inside modern buildings.

Research into the use of biological means of solving environmental problems, both on Earth and in space habitats, has been carried out for many years by researchers at NASA. Plants take substances out of the air through the tiny openings in their leaves, but research also shows that plant leaves, roots and soil bacteria are all important in removing trace levels of toxic vapors.

NASA research has consistently shown that living, green and flowering plants can remove several toxic chemicals from the air in building interiors. You can use plants in your home or office to improve the quality of the air to make it a more pleasant place to live and work.

A list of air filtering plants was compiled by NASA as part of the NASA Clean Air Study, which researched ways to clean air in space stations. As well as absorbing carbon dioxide and releasing oxygen, as all plants do, these plants also eliminate significant amounts of benzene, formaldehyde, and trichloroethylene.

TOP plants - Most effective in removing air pollutants:

1. Chinese evergreen (Aglaonema modestum)
2. Peace lily (Spathiphyllum 'Mauna Loa')
3. Janet Craig dracaena (Dracaena deremensis 'Janet Craig')
4. Warneck dracaena (Dracaena deremensis 'Warneckii')
5. Bamboo palm/Reed palm (Chamaedorea sefritzii)
6. Pot Mum/Florist's Chrysanthemum (Chrysantheium morifolium)
7. Spider plant (Chlorophytum comosum)
8. Cornstalk dracaena (Dracaena fragans 'Massangeana')
9. Red-edged dracaena (Dracaena marginata)
10. Weeping Fig (Ficus benjamina)
11. Rubber Plant (Ficus elastica)
12. Gerbera Daisy/Barberton daisy (Gerbera jamesonii)
13. English Ivy (Hedera helix)
14. Selloum philodendron (Philodendron bipinnatifidum, syn. Philodendron selloum)
15. Elephant ear philodendron (Philodendron domesticum)
16. Heartleaf philodendron (Philodendron oxycardium, syn. Philodendron cordatum)
17. Snake plant/Mother-in-law's tongue (Sansevieria trifasciata 'Laurentii')
18. Golden pothos/Devil's ivy (Scindapsus aures/Epipremnum aureum)

These are plants that you can find anywhere, at the florist or even at the roadside. Using living plants is an environmental-friendly way to reduce air pollution. So please do Earth a favour, put some plants at home to keep the air fresh, and plant a tree while you're at it.

Visit: www.treehugger.com
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Life Elsewhere in the Universe

Exobiology

Also known as astrobiology, is the study of life in space, combining aspects of astronomy, biology and geology. It is focused primarily on the study of the origin, distribution and evolution of life.

Some major astrobiological research topics include:

• What is life?
• How did life arise on Earth?
• What kind of environments can life tolerate?
• How can we determine if life exists on other planets?
• How often can we expect to find complex life?
• What will life consist of on other planets?
• Will it be DNA/Carbon based or based on something else?
• What will it look like?

Is there alien life?



First allow us make a few assumptions:

• That there is an infinite amount of stars in the universe, only a few billions could be seen through our powerful telescopes.
  
• Our universe is currently in the "child" stage, the Stelliferous Era. Even today, new galaxies are still being born.
• Time is relative, not constant. The flow of time is different for everyone, and for every place.
• Since the universe is vast, there should be at least some simple form of life; plants and animals.
• Among these primitive life forms, some should have evolved to be intelligent, in aspects of communication, logic, culture, etc.
  

Given the statistics, it's very probable that we could find alien life. However, we are searching for intelligent alien life, which is a whole new level. It's possible we may not succeed in our lifetime. Something for future generations.

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