It is an obvious fact of life that weather and the seasons are periodic.  Spring becomes summer; summer, fall; fall, winter; and winter, spring again.  And with the change in seasons temperatures rise, fall, and rise again. Vineyards and the grapes they produce depend on this annual cycle. New shoots appear in spring.  Grape clusters form and mature in the heat of summer.  Grapes ripen and are picked in fall.   And the plant hardens and is pruned in winter after the last season's shoots have formed the buds for the next year's crop.

Grapes are grown world wide in temperate climates. Ideal temperature variations range from a maximum of near 100°F in summer to a minimum of 5-10° below freezing in winter. California, Oregon, and Washington are three of the most important wine growing regions in the US.  The map below shows counties in each of these states along with the area around Oliver, British Columbia. In this series of lessons you will explore the changes in seasonal temperatures over the last century in three of the US counties: Napa County, California, Yamhill County, Oregon, and Yakima County, Washington as well as Oliver, BC and   examine the implications these changes may have for the production of wine grapes.  Specifically, you will learn:

• to interpret the periodic patterns typical of temperature change and many other natural phenomena using sine curves,
• how to transform the equation of a basic sine curve to model real world data based on period, amplitude and shifts both vertically and horizontally, and
• a bit about climate and grape culture.

1) According to the data in the map, how does the overall grape acreage in Oregon compare to that in California?

2) Turn off the grape layers and explore the basemap under the leading counties in grape production in each region. What geographic characteristics do many of these counties have in common?

3) Although the two counties are roughly the same size, grape acreage in Napa County in California is about nine times that of Yamhill County in Oregon. Napa County's farm economy is almost all grapes. Turn off the county layers and turn on the Vineyard layer and zoom in on Napa County. Notice the almost solid belt of vineyards running northwest to southeast across the county. What geographic feature of the county underlies these vineyards?