Yakima WATERS Mini Lesson
Introduction to Rain Shadow Effect
Targets and Assessment
WA Science GLEs Addressed:
 9-12 INQB, INQC, APPD, ES2B,
Lesson Parameters
Content Area: Earth Science
Overview: Follow up to Local Climate focusing on cause of
Precipitation amounts on eastern slope of Cascades
Grade Level: 9th
Assessments:
 Integrated into Climate Unit Summative
Assessment.
Suggested Time: 1 Class Period
Special Materials:
 None
Learning Outcomes:
Knowledge: Causes of Rain Shadow Effect: wind patterns, topography, location
Skill: Ability to examine data tables (precipitation) along with topographic maps to determine potential
causes of weather.
Science Concept Background: Ellensburg is located near the tail end of a succession of towns which display
precipitation trends that display the basic definition of the Rain Shadow Effect. This is the result of wind
patterns forcing warm/moist air against a mountain range forcing the rapid cooling and release of moisture.
This results in heavy precipitation at the near the summit and a decreasing amount of precipitation as the air
moves across and down from the mountains. This is a key element in understanding the climate of Ellensburg
and surrounding areas in the Yakima Watershed.
Materials:
Whiteboard and Pen
Computer
Projector
Procedure: Class begins with question and answer session in regards to climate data analyzed in prior class
period. This is a good time to gauge the students understanding of the information they were given. They are
then asked to explain why Seattle gets more precipitation than Ellensburg, rain shadow effect may be a
response but generally few understand what it truly implies. The instructor then takes the students through
the process of drawing a diagram that displays the flow of air, change in temperature, and condensation and
release of moisture. Using the climate website the class looks up the precipitation data from both sides of the
Snoqualmie summit, Easton, Cle Elum and Ellensburg.
Key questions: Why is there more precipitation in Seattle than Ellensburg?
What happens to moisture in air as the air cools?
Extension(s): Students can utilize the climate website to locate other locations of a rain shadow effect. This is
effective in eliminating the belief that closeness to water causes increased amounts of rain fall. The Olympic
Peninsula providing a good example when comparing precipitation in Forks and Port Angeles, and for an
international example they can look at precipitation in Lima compared to locations on the other side of the
Andes Mountains.
Teaching Tips: This lesson can trend towards a typical lecture approach, to avoid this it is suggested that
students are given many opportunities to interject and express opinions/experiences and questions.
Supplements:
www.worldclimate.com
Author: Holly Eagleston, Yakima WATERS Project, CWU, Fall 2009