# How big can a raindrop get?

The laws of physics restrain raindrops from getting too large before they break up into smaller droplets. Thus, about 0.25 inches (0.635 centimeters) is the largest a drop can get and still have the surface tension of the water hold it together.

# How is rainfall measured?

Agencies like the National Weather Service use very accurate devices that measure rainfall to the nearest one-hundredth of an inch. The devices, known as rain gauges or tipping-bucket gauges, collect rainwater at a point unaffected by local buildings or trees that may interfere with the rain.

A NOAA rainwater collector positioned near Mauna Loa, Hawaii, checks for acid rain. (photo Commander John Boitniak, NOAA Corps)

# What is meant by a trace of precipitation?

When the amount of rainfall is too little to be measured by a standard rain gauge, the precipitation is labeled a "trace."

# How can I measure how much rain falls where I live?

Any container with a flat bottom and flat sides can measure rainfall. The width of the top of the container must be the same as at the bottom of the container, but the diameter does not matter. It could be a device purchased for measuring precipitation or something as simple as a coffee can.

# What is the Bruckner cycle?

The Bruckner cycle refers to the idea that periods of unusually wet years are then followed by dryer-than-normal years in a cycle that alternates about every 35 years, though it may fluctuate by as little as 20 and as much as 50 years. It is named after German geographer and meteorologist Eduard Bruckner (1862-1927). The cycle is also related to colder and warmer years. Bruckner, who was also very interested in climate change and glacier advancement and retreats, based his theory on his research into glaciers and tree rings. Because there is so much variation in these

Can some people with arthritis or aching joints predict the rain?

Many people claim that they can feel a rain storm approaching because they will feel an ache in their knee, a throb in a tooth, or some other pain in their bodies. In a research study conducted by the University of Pennsylvania, scientists learned that, indeed, people with arthritis could sense when humidity levels went up and pressure dropped, both of which are good indications of an approaching storm.

cycles, though, climatologists have become much more interested in both the shorter-term and longer-term changes in climate.

# Where does it rain the most in the United States?

Mt. Wai'ale'ale, on the island Kauai in Hawaii, receives a whopping average of 460 inches (1,168 centimeters) of rain a year—that's over 38 feet (about 12 meters) of rain per year!

# What place has the most rainy days every year?

When it comes to the number of rainy days per year, the winner is again Mount Waialeale on Kauai, Hawaii, with up to 350 rainy days annually.

# Where is the rainiest place on Earth?

The wettest place in the world, in terms of total rainfall, is Mawsynram, India, which drowns in 468 inches (1,188 centimeters) of rain each year, mostly because of monsoon rains. Nearby is Cherrapunji, India, which receives 460 inches (1,170 centimeters) of rain. Second place, though, goes to Tutunendo, Colombia. Here, the average annual rainfall is 463.4 inches (1,177 centimeters). Unofficially, Lloro, Columbia, endures 523 inches (1,328 centimeters) of rain annually, but no verified measurements have been taken to confirm this claim.

# What are ombrophobia and homichiophobia?

Ombrophobia is an irrational fear of the rain, while homichiophobia is a fear of fog. How much does it rain in the Amazonian rainforest?

The largest rainforest in the world surrounds the Amazon River basin, most of which lies within the borders of Brazil. Here, the average rainfall is 80 inches (200 centimeters) annually. Interestingly, despite all the rain and thick forest growth, the soil in the Amazon region is quite sterile and not well suited to farming.

Are stories about fish, frogs, and insects raining down from the skies real?

While the old saw about "raining cats and dogs" is just an expression, there have been reliable reports of very strange rains during which people are pummeled by frogs, grasshoppers, fish, and other bizarre creatures. For instance, in 1873 it was reported in a Scientific American article that frogs fell from the sky during a storm in Kansas City, Missouri. Both frogs and toads rained down on Minneapolis, Minnesota, during a 1901 storm; more recently, in 1995, a frog storm was reported in Sheffield, England.

One possible explanation for amphibian rain is waterspouts carrying frogs and toads up into the air, where prevailing winds then dump them onto a distant location. The same sort of theory might apply to reports of raining fish. A couple living in Folsom, California, for instance, reported a fish rain in September 2006, and earlier that year a similar eye-witness account came from Manna, India. Scientists were not incredulous, explaining that waterspouts can kick up winds of 200 miles (320 kilometers) per hour that have been known to lift objects as big as sailboats.

Other creatures, such as birds and flying insects, have been victims of weird weather, as well. It's not too much of a mental leap to conceive birds being caught in a strong storm that could injure or disorient them, causing them to fall out of the sky. Insects such as grasshoppers and crickets could just as easily be victims of such storms. In 1988, for example, meteorologists speculated that a swarm of red grasshoppers in Africa was caught up in strong winds and blown all the way to the Caribbean, where they landed in a massive insect rain shower.