Research Frequently Asked Questions

updated: 20.03.2016
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How often does lightning strike the Earth?

There are about 50-100 lightning discharges every second somewhere on the Earth.  At anytime there are about 1000 active thunderstorms.  So somewhere on the Earth lightning is happening at this very second.

What is thunder?

Lightning heats the air to temperatures of 30,000 degrees (5 times hotter than the surface of the sun), heating the air around the lightning channel.  This rapid heating of the air results in the fast expansion of the air, at speeds greater than the speed of sound.  This results in a shock wave (sonic boom) that is the cause of the thunder.  For this reason thunder always comes AFTER the lightning.

Where is the most lightning on Earth?

Lightning and thunderstorms are most frequent in the tropical regions, and the area with the most lightning per unit area is the Congo basin in central Africa.

Is lightning distributed randomly around the globe?

No, most lighting and thunderstorms are located over the continental regions of the world.  This is only about 30% of the Earth’s area, but has about 90% of the thunderstorms.  

Does lightning only occur in winter?

Actually, only in a few places in the world (Israel, California, North Africa, Japan) do we see lightning in the winter season.  Most lightning occurs in the summer season, with the southern hemisphere having most lightning during Dec-Feb (their summer) while the northern hemisphere has most of its lightning during June-Aug (our summer).

Why is there no rain in Israel in the summer, even though it is very humid?

For rain to form we need the humid air to rise, cool, condense into droplets, and to grow to the size of raindrops.  Due to the large scale circulation patterns in the summer, the air is blocked from rising too high above the surface, not allowing for storms to form in the summer.

Is the Earth’s atmosphere warming?

Yes, evidence shows that in the last 150 years the Earth’s temperature has increase by about 1 degree.  Although that does not sound like a lot, a one degree increase in our body temperature makes us feel pretty cranky and sick.

Why is the globe warming?

We believe it is due to increases in “greenhouse” gases in the atmosphere that trap in the Earth’s heat and don’t let the Earth cool as much as it did before.  There is strong evidence that we (humans) are the cause of the dramatic increase in greenhouse gases in the atmosphere since the Industrial Revolution.

How will this impact our lives?

To look into the future we need to use computer models to simulate and forecast what may happen.  Models predict an additional few degrees of warming by the end of this century, with impacts on agriculture, water resources, our health, natural hazards like hurricanes and floods, sea level rise, fisheries, and even perhaps conflicts between countries over limited resources.

Does the ozone hole impact global warming?

Not directly.  The ozone hole is produced by a specific type of gas (CFC) used in our refrigerators, air conditioners, dry cleaning, etc. until recently.  While these gases resulted in the depletion of the ozone layer, that itself does not cause warming of the Earth.  The main effect is to increase harmful ultra-violet radiation reaching the surface, which is dangerous to people, animals, and plants.  However, CFC do also trap heat (hence their use in air conditioners and refrigerators), and hence their increase in the atmosphere also contributes to global warming.

Why are there no hurricanes in Israel?

For hurricanes to develop and intensify they need vast expanses of warm ocean waters, above 28C.  While we do have such warm waters in Israel in the summer, the Mediterranean is too small for such huge storms to develop in our region.

What is the difference between a tornado and a hurricane?

A tornado occurs only over land, while a hurricane is mainly over the oceans.  A tornado is much smaller (maybe 1 km width) while a hurricane is huge (1000 km width).  Tornadoes last for only a few minutes while hurricanes can be around for 2 weeks.  Damage from tornadoes is mainly from strong winds, while hurricanes have strong winds, heavy rains, and cause heavy flooding along coastlines.  Tornadoes form mainly in mid-latitudes, while hurricanes form mainly in the tropics.

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