High School
Earth Science
Week 5: May 11-15
Describe the temperatures you would expect if you measured at the surface of the beach and at a depth of �12 inches in the sand.
If you stood waist deep in the water and measured the water’s surface temperature and its temperature at a depth of 12 inches, how would these measurements compare to those taken on the beach?
Answer: The temperature of the surface sand would be warm or hot from the solar radiation. Since radiation does not penetrate deep into the earth, the temperature at a 12 inch depth would be cooler.
Answer: The water temperatures would be cooler than those on the land, �and would be similar at the surface and at a 12 inch depth.
Essential Vocabulary
Essential Vocabulary
Essential Vocabulary
For the Record: Air Temperature Drops
Changes in temperature are probably the most noticed changes in the weather.
Air temperatures over a large area can be examined using isotherms. Isotherms are lines that connect point of equal temperatures-much like contour lines connected points having the same elevation.
Isotherms
Smartfigure 16.25 Isotherms
For the Record: Air Temperature Drops
The amount of temperature change per unit of distance is called the temperature gradient. Looking at the isotherms in the previous slide, notice that they are closer in Colorado and Utah, which means they have a steeper temperature gradient. (Just like contour lines which are closer together indicate a rapid change in elevation.)
Why Temperatures Vary: �The Controls of Temperature
Latitude is a temperature control. Variations in sun angle and length of daylight depend on latitude. These factors cause areas at equatorial latitudes will be warmer and areas near the poles will be colder. Areas between the poles and the equator will also experience seasonal changes in temperature to account for the tilt of Earth’s axis and the revolution of Earth around the sun. If you remember from previous lessons, the angle of the sun’s rays and the length of daylight play a big role in how much the Earth heats up.
Why Temperatures Vary
Different surfaces on Earth also have different abilities to absorb and radiate solar radiation. The atmosphere is heated by energy radiated off the surface of the planet.
Land heats up more rapidly and to higher temperatures than water. However, it also cools more rapidly, and to lower temperatures than does water. This is because water has a higher specific heat. It takes more energy to raise the temperature of 1 gram of water 1º C than it does to raise the temperature of 1 gram of “land” 1º C. Because water has the ability to hold on to its heat energy, warm ocean currents can have a moderating effect on the land areas they pass by on their way toward the poles.
Differential Heating of Land and Water
Which surface -- land of water -- has the highest temperatures?
Answer: Land
Mean Monthly Temperatures for Two Locations in Canada
Look at the graph on this slide. Vancouver has a much smaller annual temperature range than Winnipeg because of the strong marine influence of the Pacific Ocean.
Mean Monthly Temperatures for Two Locations in Canada
Altitude can affect the temperature of an area. Quito and Guayaquil, two cities in Ecuador, are found at the same latitude. They should have the same mean temperatures. However, Guayaquil’s mean temperature is 77º F and Quito’s is 55º F. This difference in temperatures is due to elevation. Guayaquil is only 40 feet above sea level. Quito is high in the Andes Mountains-9200 feet above sea level.
Controls of Temperature
Both these cities are located at a latitude of 16° South. Why do you think LaPaz experience cooler temperatures than Concepcion? Vancouver has a much smaller annual temperature range than Winnipeg because of the strong marine influence of the Pacific Ocean.
Answer: Because La Paz has a higher altitude than Concepcion. (La Paz has an altitude of 4103 meters-13,461 feet. Concepcion is at an elevation of 490 meters-1608 feet.)
Geographic Position
Geographic position can also influence the temperature of a location.
Coastal Locations: A coast where the wind blows from the ocean to the shore is called a windward coast. The air that blows from the ocean will bring a moderating influence to the coastline-cool summers and mild winters. A coastline where the wind blows from the land to the ocean is called a leeward coast. Leeward coasts will have continental temperature patterns with greater annual temperature ranges.
Controls of Temperature
Geographic Position
Both Eureka, California and New York City are coastal cities. Both are located at about the same latitude. They do, however, have different monthly mean temperature patterns. Eureka’s temperatures do not fluctuate as much as New York’s because Eureka is on a windward coast. This means the air blows from the ocean to the land. Since water does not experience the rapid changes in temperature that the land does, air that flows from the ocean to the land will help to moderate the temperature of the land. Areas on windward coasts have cool summers and mild winters.
Cloud Cover & Albedo
Clear days are warmer than cloudy ones because the sun can go all the way through the atmosphere and be absorbed and re-emitted by the Earth. Also, clouds will reflect solar radiation back into space. Clear nights, however, are cooler than cloudy nights, because the clouds act like a blanket and help hold heat near the Earth’s surface instead of it escaping into space. Snow and ice covered areas also reflect sunlight instead of letting the Earth absorb it. They are said to have a high albedo.
Controls of Temperature
Smartfigure 16.32
Daily cycle of temperature
World Mean Sea-Level Temperatures in January
Smartfigure 16.34 World Mean Sea-level Temperatures
World Mean Sea-Level Temperatures in July
World Distribution of Temperature
Study the two previous slides. The isotherms trend east and west and show a decrease in temperature as you move from the equator toward the poles. Notice that the isotherms shift north and south from season to season and that there is a greater variation in temperature over land than water.
16.9 World Distribution of Temperature
World Distribution of Temperature
World Distribution of Temperature
Review Your Understanding: #1
Determine which statements refer to weather and which refer to climate. (Note: One statement includes aspects of both weather and climate.)
Review Your Understanding: #2
This map shows the mean percentage of possible sunshine received in the month of November across the 48 contiguous United States.
Review Your Understanding: #3
Refer to this chart to answer the following questions about temperatures in New York City:
Review Your Understanding: #4
Which of the three mechanisms of heat transfer is clearly illustrated in each of the following situations?
Review Your Understanding: #5
On which summer day would you expect the greatest temperature range? Which would have the smallest range in temperature? Explain your choices.
Review Your Understanding: #6
The Sun shines continually at the North Pole for 6 months, from the spring equinox until the fall equinox, yet temperatures never get very warm. Explain why this is the case.
Review Your Understanding: #7
The circumference of Earth at the equator is 24,900 miles. Calculate how fast someone at the equator is rotating in miles per hour. If the rotational speed of Earth were to slow down, how might this impact daytime highs and nighttime lows?
Review Your Understanding: Answers
#1:
#2:
#3:
Review Your Understanding: Answers
#4:
#5:
Choice C would provide the greatest temperature range because clear skies during the day allow a great deal of solar radiation to reach the surface and clear skies at night allow Earth’s longwave radiation to escape. Choice D would have the smallest range because cloudy skies would allow little shortwave radiation into the atmosphere and clouds at night would prevent radiation from escaping.
Review Your Understanding: Answers
#6:
Despite the long period of solar radiation continually reaching the North Pole, the temperatures never get very warm because the sun angle is quite low and never gets above 23½° during this entire time, thus the intensity of solar radiation is always low as well.
#7:
24,900 miles / 24 hours = 1038 miles/hour. If Earth’s rotational speed were to slow down, daytime high temperatures would be higher and nighttime low temperatures would be lower.
Vocabulary Quiz
Write the letter of the correct definition on the next few slides next to each of the words.
Vocabulary Quiz
Vocabulary Quiz
Vocabulary Quiz
Vocabulary Quiz
Vocabulary Quiz: Answers
Elaborate: Mt. Pinatubo Eruption
Following a major volcanic eruption that sends huge volumes of debris and gases into the atmosphere, global temperatures tend to decrease over a period of several months to perhaps a year or two. The volcanic debris and aerosols (primarily droplets of sulfuric acid) serve to block and reflect a portion of the incoming solar radiation, thus reducing the amount of heat energy that reaches Earth’s surface. A change in temperature might impact the biosphere because many species are adapted to specific temperatures.
Do & Connect: Earth’s Axis Inclination
If Earth’s axis were perpendicular to the plane of its orbit instead of being inclined 23½°, the equator would receive vertical (90°) rays from the Sun throughout the entire year. Therefore, the altitude of the noon Sun and length of day would remain the same at each latitude throughout the year, and no seasonal variations would occur.
If the tilt of the Earth’s axis was 40°, seasonal variations would be more extreme than they are now—warmer summers and colder winters in both hemispheres. The Arctic and Antarctic Circles would be at 80° North and South.
Riddle
If a band plays music in a thunderstorm, who is most likely to get hit by lightning?
Answer
The conductor.