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Climate Patterns across the United States

Authors: Kirstin A. Bittel and Rachel Hughes
Editor: Stephanie Nardei

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Time: 2 class periods
Preparation Time: 5 minutes reserving computer lab
5-10 minutes making copies

Access to computer lab
Sample climograph overhead

Map of United States

Köppen Climate Classification System:

Why do climate patterns vary across the country? Students are challenged to identify patterns in climate data across the US that might give them insight as to the role of the impact of land and water masses on climate. Students use the internet to collect climate data and their understanding of global climate patterns to piece together an explanation of major climate patterns within the USA. They will also be introduced to climographs.

Students will be able to:

  1. Articulate difference between climate and weather using examples in a written statement.
  2. Using climate data (temperature, precipitation etc.) from across the country, students describe climate patterns for various parts of the United States on a map.
  3. Explain how land and water masses might affect temperature and precipitation using the climate data and share with the class via presentation and discussion.

National Science Education Standard:
CONTENT STANDARD D: Earth and Space Science
• Earth systems have internal and external sources of energy, both of which create heat. The sun is the major external source of energy. Two primary sources of internal energy are the decay of radioactive isotopes and the gravitational energy from the earth’s original formation.

• Heating of earth’s surface and atmosphere by the sun drives convection within the atmosphere and oceans, producing winds and ocean currents.

• Global climate is determined by energy transfer from the sun at and near the earth’s surface. This energy transfer is influenced by dynamic processes such as cloud cover and the earth’s rotation, and static conditions such as the position of mountain ranges and oceans.

• Movement of matter between reservoirs is driven by the earth’s internal and external sources of energy. These movements are often accompanied by a change in the physical and chemical properties of the matter. Carbon, for example, occurs in carbonate rocks such as limestone, in the atmosphere as carbon dioxide gas, in water as dissolved carbon dioxide, and in all organisms as complex molecules that control the chemistry of life.

Teacher Background
The climate of a particular place is affected by a number of factors. As addressed in earlier lessons, the temperature differences between latitudes drive the general circulation of the atmosphere. However, other factors impact climate including oceans, longitude, land mass distribution and mountain ranges.

Longitude is especially important to understanding climate in the mid-latitudes (upper 20’s to low 40’s) of both the Northern and Southern hemispheres. At the west side of the great continents you typically get very dry climates in the mid latitudes. For example, in the Southwestern states the climate is primarily dry, while the same latitude in a southeastern state may be described as having a humid and hot climate.

Mountain ranges affect regional and local climates by both diverting prevailing winds and by forcing the deposition of moisture as the air rises when it meets the mountains. Here in the United States the Chinook winds leeward of the Rockies and Santa Ana winds in California impact regional and local climate.

Ocean currents and surface water temperatures play a significant role in climate. The Gulf Stream is an ocean current that has a significant effect on the weather of Northwest Europe. El Niño and La Niña are the effects of irregular oscillations in ocean currents whose mechanisms have been uncovered only in the past few decades. These oscillations have dramatic impacts on climatic patterns in North America and South America as well as Australasia.

Locations that are at the same latitude, but that might be distinguished from one another as coastal or continental interior, can differ significantly in climate. Generally, coastal locations (or those near large bodies of water like the Great Lakes) experience milder and more humid climate all year as compared to their non-coastal latitude equivalents. The interiors of large land masses experience a more dramatic range of temperatures between summer and winter resulting in hot dry summers and cold winters.

Related and Resource Websites

Daily Normal Maximum Temperature (US)

Daily Normal Minimum Temperature (US)

Daily Mean Temperature (US)

Normal Precipitation (Inches – US)

Köppen Climate Classification System

Köppen Global Climate Classification Map http://www.uwmc.uwc.edu/geography/100/koppen_web/koppen_map.htm

Climograph Demo Information

What is Drought? Climographs of Selected U.S. Cities

Monitoring Drought? Climographs of Selected U.S. Cities

Maps, Climographs and other Graphs

Image of a Climograph





















Day One

Have the following questions written on the board for students to answer when they enter the class: Explain the term climate. Is it different from the concept of weather? Explain giving examples. [Climate in a narrow sense is usually defined as the “average weather”, or more rigorously, as the statistical description in terms of the mean and variability of relevant quantities over a period of time ranging from months to thousands or millions of years. The classical period is 30 years, as defined by the World Meteorological Organization (WMO). These quantities are most often surface variables such as temperature, precipitation, and wind. Climate in a wider sense is the state, including a statistical description, of the climate system.[1] (http://www.grida.no/climate/ipcc_tar/wg1/518.htm)]

1. What do you know about the climates in different parts of the United States? Explain giving examples. [The arid southwest, the wet, temperate Northwest etc.]

2. Allow students time to write their answers and share their ideas with the class. While this should be a review of middle school science, establish that the students have a clear idea of the difference between climate and weather.

3. Tell students that today they will be going to the computer lab to look at the climate across the United States. They will be looking for two things: 1) differences in average maximum and minimum temperature and 2) differences in average rainfall.

4. Divide the class into groups. Have each group focus on two different regions or states of the United States. Take the groups to the computer lab to begin looking at the websites listed above.

5. Once students have reviewed the tables of data they should create a climograph (a climograph plots average temperature and precipitation for a specific region) for their area and then place it on the map. Please note that the sample climograph does not include maximum and minimum temperatures, but the data sets given do.

6. From the data students have collected they should come up with a short paragraph describing the climate in that region referencing the data.

Day Two

1. Yesterday students should have written a short paragraph describing the climate in their areas. Now introduce them to the Köppen Climate Classification System. Given the data they have what is the climate classification for those areas? Does that match the description they had?

2. Looking at a map of North America can they come up with an explanation for the particular climate pattern they see in their area?

3. Have groups present their findings to the class. What patterns did they see?

4. As each group presents, have the class reassess the big-picture. How does the new data add to the current class opinion of the climate patterns for the United States? How does it alter that picture and force the class to reformulate their ideas? Have the groups write their climate classification assessment on an overhead map of the USA or on the board as they talk.

5. After all groups have presented, ask students to write a personal explanation of climate patterns in the United States. They should write this explanation in the style of questions. For example “Is the average amount of precipitation in X affected by its position to the east of the Rockies? Is the precipitation higher on one side of the Rockies from the other? Why?” Tell students that over the next week or so, they will be investigating several phenomena that directly affect the climate in the United States and hopefully answer the questions that they have asked. The physical geography that affects the United Sates also affects the rest of the world. To reiterate this point show students the Köppen Global Climate Classification Map at http://www.uwmc.uwc.edu/geography/100/koppen_web/koppen_map.htm

Embedded Assessment

1. Can students distinguish between the concepts of weather and climate? The warm up provides opportunity for a written assessment of their understanding.

2. A pre-assessment of students’ knowledge and ability to articulate reasons for climate patterns across the country can be taken through class discussion and notebook written responses.

3. Using data, students describe the patterns and create a climograph that can be assessed for both ability to produce an accurate climograph and ability to interpret it appropriately with and without the Köppen Climate Classification System.


PULSE is a project of the Community Outreach and Education Program of the Southwest Environmental Health Sciences Center and is funded by:

NIH/NCRR award #16260-01A1
The Community Outreach and Education Program is part of the Southwest Environmental Health Sciences Center: an NIEHS Award


Supported by NIEHS grant # ES06694

1996-2007, The University of Arizona
Last update: November 10, 2009
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