The Handy Geography Answer Book. Paul A Tucci

United States) experience greater extremes in temperature than do places that are closer to an ocean. These inland areas experience continentality. It might be very hot during the summer, but it can also get very cold in winter. Areas close to oceans experience moderating effects from the ocean that reduce the range in temperatures.

      What are the horse latitudes?

      Horse latitudes are high-pressure regions, more formally known as subtropic highs, which are warm and don’t have much wind. Legend has it that the lack of wind sometimes caused sailors of the sixteenth and seventeenth centuries to throw their horses overboard in an effort to conserve water on board. That’s how the region, centered around 30° latitude, got its name.

WEATHER

      How does land turn into desert?

      The process known as desertification is complicated and results from such activities as overgrazing, inefficient irrigation systems, and deforestation. It is most widespread in the Sahel region of Africa, a strip of land along the southern margin of the Sahara Desert. The Sahara grows larger because of desertification. Desertification can be reversed by changing agricultural practices and by replanting forests.

      As water use rises due to agriculture and increasing populations, lakes and even small seas are disappearing. The Aral Sea in Uzbekistan, for example, has almost disappeared over the last fifteen years.

      What are Fahrenheit and Celsius?

      Fahrenheit and Celsius are two common temperature scales used throughout the world. Temperature in Fahrenheit can be converted to Celsius by subtracting 32 and multiplying by five; divide that number by nine, and you have Celsius. Conversely, you can convert Celsius to Fahrenheit by adding 32, multiplying by nine, and finally dividing by five. Kelvin, a system used by scientists, is based on the same scale as Celsius. All you have to do is add 273 to your Celsius temperature to obtain Kelvin. Zero degrees Kelvin is negative 273° Celsius.

      What is a low high temperature and a high low temperature?

      When meteorologists look at daily temperature, there is always a low and a high temperature for each day. If the high temperature is the coldest high temperature for that day or for the month, you have a new record—a new low high. Conversely, if the low temperature for a day is quite warm and breaks records, that’s a new high low!

      Why is it hotter in the city than in the countryside?

      Cities have higher temperatures due to an effect known as the urban heat island. The extensive pavement, buildings, machinery, pollution from automobiles, and other things urban cause an increase in warmth in the city. Cities such as Los Angeles can be up to five degrees hotter than surrounding areas due to the urban heat island effect. The term comes from temperature maps of cities where the hotter, urban areas look like islands when isotherms (lines of equal temperature) are drawn.

      What are some world weather records?

      The following are some amazing weather records. The wettest: Cherrapunji, and the town of Mawsynram nearby in India, near the border of Bangladesh, have the highest average rainfall per year in the world, averaging 467 inches (11,872 mm); the coldest: the East Antarctic Plateau, Antarctica, with a measurement of –136° Fahrenheit (–93.2° Celsius); the driest: Dry Valleys of Antarctica which receives 0 inches (0 centimeters) of rainfall per year; and the hottest: Lut Desert, Iran, which has sizzled at 159.3° Fahrenheit (70.7° Celsius) in five of the seven years from 2004 to 2009.

      Why is it more likely to rain in a city during the week than on the weekend?

      Urban areas have an increased likelihood of precipitation during the workweek because intense activity from factories and vehicles produce particles that allow moisture in the atmosphere to form raindrops. These same culprits also produce warm air that rises to create precipitation. A study of the city of Paris found that precipitation increased throughout the week and dropped sharply on Saturday and Sunday.

      What does a 40% chance of rain really mean?

      When the morning weather report speaks of a 40% chance of rain, it means that throughout the area (usually the metropolitan area), there is a four in ten chance that at least 0.001 of an inch of rain (0.0025 centimeters) will fall on any given point in the area.

      Why is it more wet on one side of a mountain than the other?

      It’s much more wet on one side of a mountain than the other because of a process known as orographic precipitation. Orographic precipitation causes air to rise up the side of a mountain range and cool off, creating storms. The storms deposit a great deal of precipitation on that side of the mountain and create a rain shadow effect on the opposite side of the range. The Sierra Nevada Mountains are an excellent example of orographic precipitation because the mountains of the western Sierras receive considerable rainfall (far more than California’s Central Valley), while the eastern Sierras are quite dry.

       Why are there so many discrepancies in the world records of weather?

      The discrepancies in the data reflect the length of time that we use to measure weather phenomena. Some records were set by observing the weather over decades; others only occurred during the span of a few years, months, or even hours or minutes.

      What is a rain shadow?

      When the moisture in the air is squeezed out by orographic precipitation, there’s not much left for the other side of the mountains. The dry side of the mountain experiences a rain shadow effect because they are in the shadow of the rain.

      What is a thunderstorm?

      Thunderstorms are localized atmospheric phenomena that produce heavy rain, thunder and lightning, and sometimes hail. They are formed in cumulonimbus clouds (clouds that are big and bulbous) that rise many miles into the sky. Most of the southeastern United States has over forty days of thunderstorm activity each year, and there are about 100,000 thunderstorms across the country annually. Thunderstorms are different from typical rainstorms because of their lightning, thunder, and occasional hail.

      What are monsoons?

      Occurring in southern Asia, monsoons are winds that flow from the ocean to the continent during the summer and from the continent to the ocean in the winter. The winds come from the southwest from April to October and from the northeast (the opposite direction) from October to April. The summer monsoons bring a great deal of moisture to the land. They cause deadly floods in low-lying river valleys, but they also provide the water southern Asia relies upon for agriculture.

      What is the origin of the word “monsoon”?

      The word “monsoon” comes from several source languages, including from the Portuguese word moncau, the Arabic word mawsim, and the early Dutch word monsun.

WIND

      What are dust devils?

      These columns of brown, dust-filled air, which can rise dozens of feet, are not as evil as the name suggests. They are caused by warm air rising on dry, clear days. Winds associated with dust devils can reach up to 60 miles (96.5 km) per hour and cause some damage, but they are not as destructive as tornadoes and usually die out pretty quickly.

      What causes the wind to blow?

      The Earth’s atmospheric pressure varies at different places and times. Wind is simply caused by the movement of air from areas of higher pressure to areas of lower pressure. The greater the difference in pressure, the faster the wind blows. Some detailed weather maps show wind speed along with isobars (areas of equal air pressure) indicating the level of air pressure.

      In which direction does the west wind blow?

      It blows from the west to the east. Wind direction is always named after the direction from where it originates.

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