Do rivers always flow from the north to the south?

While some oblivious people think that rivers always flow from the north to the south (a term some even call downhill!) but rivers always flow with gravity (unless modified by humans). There are countless examples of rivers that flow from the south to the north (in both hemispheres), such as the Ob in Russia and the Mackenzie in Canada.
An interesting analogy was brough up in the Geography Forum - would you fly to Seattle, rent a car, and coast all the way to Los Angeles? Just because south is at the bottom of the map, doesn't mean it's lower in elevation.

From which direction does a north wind blow?
Winds (such as the north wind) are named for the direction they blow from so the north wind would blow from the north and a west wind would blow from the west (and to the east).
An cup anemometer or wind vane, which are used to measure wind speed and indicate direction, point into the wind so they'd point north during a north wind.

How do you convert snow into rainfall amounts?
Since precipitation is generally measured in inches of liquid water and not in snowfall amounts, snow is usually converted into inches of water by dividing by 10. Thus, ten inches of snow is equivalent to one inch of rain.
Light and loose snow takes more than 10 inches to make an inch of water but dense and slushy snow takes less.

How does the boiling temperature of water change with altitude?
While at sea level the boiling point of water is 212° Fahrenheit, for ever 500-foot increase in elevation, the boiling point drops one degree. Thus, at a city 5000 feet above sea level, water boils at 202°F.

How long does it take the earth to make one rotation around itself?
The earth takes precisely 23 hours, 56 minutes, and 4.2 seconds to make one rotation around itself.

How many active volcanoes are in the world?
There are approximately 1,500 active volcanoes worldwide.
A volcano is considered active if it has erupted in the last 10,000 years. Over 75% of the world's volcanoes and most active volcanoes are located in the Pacific Ring of Fire.

How many tectonic plates are on earth?
There are dozens of tectonic plates on earth but only about one seven huge plates. The largest include the African Plate, Antarctic Plate, Eurasian Plate, Indo-Australian Plate, North American Plate, Pacific Plate, South American Plate.

How much of the earth is permafrost?
About one-fifth of the earth's soil is frozen year-round (for at least two years in a row), thus deserving of the name permafrost. Much of the permafrost on earth exists at the higher latitudes, where the climates are generally cooler.

How often does a 100-year flood occur?
Large floods are often given designations as a "one-hundred-year flood" but a 100-year flood does not mean that such a flood occurs once every 100 years; instead it means that there is a one in one-hundred (or 1%) chance of such a flood occurring in a given year.
Two 100-year floods could occur a year apart or even a month apart -- it all depends on how much rain is falling or how quickly the snow melts. A "20-year flood" has a one in twenty (or 5%) chance of occurring in a particular year so it would be a less destructive flood than a 100-year flood while a "500-year flood" has a one in 500 (0.2%) chance of occurring so it would be much more catastrophic than a 100-year flood.

What are the seven seas?
Although seamen of long ago are popularly known to have stated "I've sailed the seven seas," there really wasn't a good definition of those seas. However, today, the seven seas are the North Atlantic, South Atlantic, North Pacific, South Pacific, Indian, Antarctic, and Arctic Oceans.

What effect does the Coriolis force have upon my bathtub?
It's granted that the Coriolis effect has an affect on the circulation of air and water on the planet but many people also think that the force has an effect on sinks, wash basins, toilets, bathtubs and other tiny bodies of water.
Unfortunately, small bodies of water are not affected by the Coriolis effect or bearing on whether sinks and toilets drain in one direction in the Northern Hemisphere and another direction in the Southern Hemisphere.

What is a tsunami?
Often improperly called "tidal waves," tsunamis or seismic sea waves are usually caused by earthquakes that occur near or under the ocean. These waves created by the shifting of the ground creates an intense energy that can result in a destructive wave that can cause damage to a region hundreds or thousands of miles from the tsunami's source.
Hawaii is quite vulnerable to tsunamis so the islands have a comprehensive warning and alerting system.

What is an epicenter?
An epicenter is the point on the earth's surface directly above the hypocenter of an earthquake. A hypocenter is the point where an earthquake actually occurs and it's commonly underground.

What is the Ring of Fire?
The Pacific Ring of Fire is an arc of intense seismic (earthquake) and volcanic activity stretching from New Zealand, along the eastern edge of Asia, north across the Aleutian Islands of Alaska, and south along the coast of North and South America. It is composed over 75% of the world's active and dormant volcanoes.
The Ring of Fire is located along the borders of the Pacific Plate and other tectonic plates but was noticed and described before the invention of the plate tectonics theory.

What proportion of the earth is covered by water?
The water on the earth occupies 70% of the planet, leaving land to occupy 30%.

What's the difference between a hill and a mountain?
Unfortunately, there is no universally accepted standard definition for the height of a mountain or a hill although a mountain usually has an identifiable summit. In the United Kingdom, a mountain must be over 600 meters (1969 feet) or over 300 meters (984 feet) if it's an abrupt difference in the local topography. However, some hills can be called mountains and some mountains can be called hills - it's just a matter of the original name given to the relief.

What's the difference between a stalactite and stalagmite?
Stalactites and stalagmites are formed in caves by the deposition of calcium carbonate. Stlactites are the conical deposits that form at the roof of the cave and hang downward while stalagmites are those that form on the bottom of the cave and grow upward as water drips down from above.
To remember the difference between the two, think of stalactites as holding tight ("tite") to the ceiling of the cave.

When is the coldest part of the day?
The coldest (or minimum) temperature during a 24-hour period is usually just before and during sunrise. It's then that the atmosphere has had the chance to cool off most, before receiving the rays of the sun.

Why does the earth tilt?
The tilt of the earth at 23.45° is a result of collisions with large bodies during the formation of the planets in the solar system. The size of the bodies and the angle of collision determined the tilt and the rotation of the planets. Each planet has a different tilt with respect to the planet's plane of the ecliptic.

Why is the desert so cold at night?
The very dry air of the desert holds little moisture and thus holds little heat so as soon as the sun sets, the desert cools considerably. Clear, cloudless skies also help to quickly release heat at night. Mos deserts have very low temperatures at night.