Module 3: Understanding Climate Patterns in North America

James S. Oliver III and Russell W. Graham, The Pennsylvania State University
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Initial Publication Date: July 5, 2018

Summary

Understanding the broad patterns of global climate helps in understanding more specific North American climate patterns. Understanding these climate patterns is necessary to understand the modern and past distributions of plants and animals in North America. In this activity, students are introduced to concepts of weather and climate (particularly North American temperature and precipitation patterns). Students complete a series of exercises where they analyze temperature and precipitation maps as well as historical data to learn about geographic and temporal changes in weather and climate.

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Learning Goals

By the end of this activity, participants will:

  1. Gain an understanding of relationships between the geographic patterns of climate variables and the geographic distributions of biota.
  2. Create schematic graphical representations of climate variables as a function of space.
  3. Analyze changes in climate over time.

Context for Use

This is a laboratory type exercise that can accompany a lecture series on climate change and biotic response. It can be be used for any size class since it is on line. Classes of about 20-25 are the most ideal of they are being facilitated by an instructor. This is the third in a series of 7 modules to be used by participants to understand how climate change in the past and future affects the distribution of mammal species. Each module builds on the next to introduce participants to climate patterns, change in climate through time, ecology & paleoecology and the interaction between climate and biotic distributions.

Description and Teaching Materials

Students are given background information and then asked to answer a series of questions in order to assess their comprehension of the material. The exercises in this module require that students use GoogleEarth. If they have problems with the exercises, they should reread the material, use references that are provided, or be facilitated by an instructor.

Module 3: Understanding Climate Patterns in North America (Microsoft Word 2007 (.docx) 3MB Jul5 18)

World Temperature Observations 1901-1990.kmz file

Teaching Notes and Tips

North American Climate

In the east, temperature is a function of latitude: decreasing latitude (farther north) temperature decreases and vice versa

In the west, temperature also decreases with latitude but it also decreases with altitude which creates a much more complex climate pattern in the mountainous areas.

Throughout NA precipitation decreases towards the west (increasing longitude) and vegetation responds accordingly with forest grading into grassland and then eventually desert across a transect from the east to the west.

Organisms, especially plants, respond more to effective moisture which is the amount of precipitation per year minus the amount of evaporation per year. Cooler climates have lower evaporation rates so they tend to have a higher effective moisture than an area with the same annual precipitation but a warmer climate.

Biomes - Precipitation and temperature act together to define the boundaries of biomes. Northern and southern boundaries are generally functions of temperature whereas, eastern and western boundaries are functions of precipitation. In the east, the north-south boundaries are temperature dependent grading from the south to the north: deciduous, mixed, and boreal (spruce) forests and eventually tundra. As noted above the western biomes are dependent upon moisture and have relatively narrow east-west boundaries with broad north-south boundaries.


Assessment

1. Quizes

2. Use climate maps from other continents and have students determine the relationships between latitude and longitude and climate.

3. Have students construct schematic temperature (north-south) and precipitation (east-west) graphs with latitude and longitude on the X axis. Then have the students schematically label the different biomes along the x axis as well.

References and Resources