Activity 2

Essential Question

What are the effects of latitude on climate?

Background

Latitude is the most important explanation of climate on Earth. Latitude is directly related to the amount of sunlight that arrives at the Earth's surface and how long it continues to arrive. The equator is the lowest latitude and receives sunlight directly throughout the year. The Arctic Circle and North Pole, and their counterparts in the southern hemisphere, receive no direct sunshine on their surface. There are four other elements also, but none as important as latitude. They include altitude above sea level. The thinner atmosphere at higher elevations has fewer molecules per unit of air to intercept solar energy or to transfer energy from the sun.

Physical features, such as mountains, affect climate. Many mountain ranges have a wet, windward side, and a dry, leeward side. Wind is also an important influence on climate. In some places winds bring precipitation. In other places the wind acts as a dryer, withdrawing the moisture from the soil and plants. The winds mix the atmosphere between the tropics and the high latitudes, so that Earth has temperature and precipitation patterns that form climate regions.

Proximity to large water and land bodies is the fifth major influence on climate. Large bodies of water tend to warm slowly and then radiate their energy slowly. They serve as cooling agents in early summer and warming agents in winter. Landmasses tend to warm quickly and then radiate their energy quite quickly. A good example is a desert that heats up quickly during the day, but cools off quickly in the evening. Of all these influences, latitude north and south of the equator is globally the most important.

Instructional Strategies

Strategy 1

Cause and Effect

Have students read the following passages. They tell the story of two weather observers at different latitudes. One is from Finland and the other one is from Kenya. Their daily recordings of weather are important information in classifying the climate of each place.

Printable Student View

Recording the Weather at High Latitudes - Finland

In 1957, Mrs. Rikkinen was the weather observer at a small village in Finland. She went outside to the Stevenson Screen, a white box filled with thermometers and barographs with an anemometer top, every six hours throughout the day to record the weather conditions. In addition, she entered her observations of snow, rain, clear, partly cloudy, or overcast skies, etc. in a weather station logbook. Every month the logbook was sent to Helsinki, the capital, where it was entered in the national climate database for Finland. A copy of the data was then sent to the International Meteorological Organization in Geneva, Switzerland.

In 2004, Mrs. Rikkinin was still the weather observer. A new instrument box was near her house to replace the old one. It was filled with more modern equipment. Computer-operated instruments now read temperature, precipitation, wind, sunshine, air pollution, and ultra-violate rays from the Sun. The information is sent by radio signal to the national center in Helsinki. Today she records the weather conditions without having to step outside. That is unless it snows. Measuring snowfall is a regular task during Finland's winter months. The chart shows the average temperatures over more than 40 years.

Jyvaskyla, Finland: Temperature (F) and Precipitation (Inches) Averages

City	Location	Data	J	F	M	A	M	J	J	A	S	O	N	D
Jyvaskyla	62N/26E	Ave. Temp	15	15	23	34	47	57	60	57	47	38	28	20
		Total Precip.	1.7	1.2	1.2	1.3	1.6	2.3	3.1	3.6	2.5	2.2	2.3	1.9

Recording Weather in the Low Latitudes - Kenya

Far to the south of Finland on the African continent is Kenya. Mr. Kimosop records the information four times a day near Nairobi, Kenya. Here is a summary of the information he collected for the year 2002. His information was sent to the National Weather Service Office in Nairobi, and then to the World Meteorological Organization in Geneva. Here is how he summarized the information recorded during the year.

Nairobi, Kenya: Temperature (F) and Precipitation (Inches) Averages

City	Location	Data	J	F	M	A	M	J	J	A	S	O	N	D
Nairobi	1S/37E	Ave. Temp	64	65	66	65	63	61	59	60	63	66	64	63
		Total Precip.	1.9	4.2	3.7	8.3	5.2	2.0	0.8	0.9	0.9	2.0	5.8	3.5

Connections to Math:

Calculate the total precipitation for the year for both places and record it (it is 39.2 inches for Kenya; 24.9 inches for Finland)
Calculate the difference between the warmest month in Finland and the average temperature in Kenya during the same month (it is 1 degree F).
Calculate the difference between the average temperature in February in Finland and the temperature during February in Kenya (it is 50 degrees F)

Cause and Effect:

Ask the students what the effects of latitude are on the differences between Finland and Kenya regarding:

precipitation (not very much, since both places receive more than 25 inches of precipitation. In Finland that is adequate to grow evergreen forests, while in Kenya it is adequate for grasslands with scattered trees.
temperature (50 degrees F. is a large difference in temperature between two places. For example, snow and ice would be present in Finland for most of the winter months, November – March.

Check for Understanding

Printable Student View

Would it get colder or warmer as you travel from lower to higher latitudes, explain your answer?

Strategy 2

Application

Latitude and Climate Affect People's Activities

People live and work in both Finland and Kenya. The climates are different because the places are at different latitudes on Earth. You are to play the role of persons working in each place. You are to use the temperature and precipitation chart to decide on how the climate is going to affect your work. People in many parts of the world have to adjust their daily work to weather conditions. Climate data does not tell you if it will rain certain day in November in Kenya. You know that it generally rains 5.8 inches during the month of November, so on some days it is going to rain. Will you or won't you go to work?

The students may use resource books and the World Wide Web to research information that will help then associate climatic conditions with life roles. For example, freezing weather and precipitation in January in Finland will result in snow. That will make for icy roads and will affect the work of the Ambulance attendant. Write ideas and speculations in the chart below.

Printable Student View

What will my life be like during the year?

Role	Nairobi-Latitude:	Jyvaskyla-Latitude:
Ambulance Attendant
Construction Worker-outside
Airline Pilot
Middle School Student
National Park Ranger

Scoring Guide

Check for Understanding

Printable Student View

The chart shows the annual average temperature for the coldest and warmest months for five cities in the United States.

Study the information and write a paragraph that states why the rule and table are in agreement; or why they disagree.

Temp/Precip	Duluth	Chicago	Nashville	Atlanta	Miami
Coldest Month	10	22	38	42	69 (Jan)
Warmest Month	70	78	80	80	82
Latitude	47 N	42 M	36 N	34 N	26 N

Rule: Increasing latitude has the effect of decreasing temperatures on Earth. This effect is there if you increase latitude north or south.