Chapter Review Questions

Chapter Review Questions

Try to answer the following questions on your own, then click the question to see the correct answer.

Describe each of the following measures: monthly mean temperature, annual mean temperature, and annual temperature range.

Monthly mean is a figure computed by adding the daily means for each day of the month and dividing by the number of days in the month. Annual mean is an average of the 12 monthly means. Annual range is the difference between the warmest and the coldest monthly means.

What information does an isotherm tell us?

An isotherm is a line connecting points of equal temperature, so we can visualize temperature distribution over a wide area.

What is meant by a steep temperature gradient?

A steep temperature gradient shows temperatures changing rapidly over a short distance.

Describe how temperature typically changes throughout the day. When is the warmest part of the day? When is the coldest part of the day? Why?

Temperatures generally peak in early afternoon. Although solar radiation is at maximum at noon and decreases after that time, it continues to provide more energy than is being lost for a few hours. Since the temperature is dependent on the total energy budget (gain versus loss), it continues to rise if there is a surplus. The maximum temperature occurs when solar energy gained no longer exceeds the energy loss. After the maximum is reached, temperatures will continue to fall throughout the night and reach their lowest point usually before sunrise.

What is the most important control of temperature at a given location?


How do large bodies of water affect local temperatures?

Water acts as a moderator of temperature, tempering the daily temperature range.

What role do ocean currents play in determining local temperatures?

In general, the presence of water moderates temperatures but proximity to a warm or cold ocean current can significantly affect coastal temperatures. 

Describe the effect that altitude has on temperature.

Generally, higher altitudes experience cooler temperatures and stations located high in the mountains tend to have a greater daily temperature range than do stations at lower elevations.

Give an example of how geographic position and prevailing winds influence local temperatures.

One example compares Eureka, California and New York City, located at similar latitudes but on opposite sides of the continent. Eureka, on the west coast, is strongly influenced by onshore westerly winds, which act to moderate temperatures throughout the year. New York is influenced by the same westerly winds, which now arrive from the interior of the continent and therefore tend to have more extreme temperatures.

Briefly explain the role that clouds play in controlling daily temperatures.

Clouds can block solar radiation and contribute to cooling the Earth’s surface during the day. However, at night they can absorb terrestrial radiation and aid in keeping the Earth’s surface warmer.

Are clear nights warmer or colder than cloudy nights? Clear days?

Without clouds, clear days are generally warmer and clear nights cooler.

Explain why the isotherms on a world mean temperature map like Figure 3.18 run nearly east to west. Are isotherms more likely to turn north and south over land or over water, and why?

Latitude is the primary temperature control, so the isotherms tend to follow lines of latitude. Since land heats and cools more rapidly than water, isotherms are more likely to bend over land. 

How does a liquid-in-glass thermometer work?

When the temperature changes, the liquid expands or contracts more than the glass. Because of this differential expansion and contraction, the length of the liquid column in the glass tube is a measure of surrounding temperature.

Describe how a thermistor works.

A thermistor operates due to a conductor whose resistance to the flow of current is temperature-dependent. Temperature is therefore indicated as a function of current.

Briefly describe apparent temperature.

Apparent temperature is the temperature that a person perceives. How warm or cold the air feels depends upon more than just temperature; it can also be influenced by relative humidity, wind, and the amount of sunshine.

What is a heating degree day? Cooling degree day? Growing degree day?

Heating degree days and cooling degree days are relative measures that allow us to evaluate the weather-produced needs and costs of heating and cooling. Growing degree days is a basic index used by farmers to determine the approximate date when crops will be ready to harvest.

Define windchill.

Windchill is the perceived decrease in air temperature felt by the body die to the flow of air.

What is the heat stress index, and what factors determine a heat index value?

The heat stress index combines temperature and humidity to establish the degree of comfort or discomfort. While air temperature and relative humidity are the primary factors taken into consideration, other factors such as the length of exposure to direct sunlight, wind speed, and the general health of the individual can affect the amount of stress a person will experience.