Types of Rainfall & Ocean CurrentsWorld Climate PatternsWorld Geo 3200/3202Unit 2, Chpt 4November 2010

Outcomes

•In this lesson you will: •2.3.6 Define the terms windward,

leeward, and rain shadow. (k) •2.3.7 Examine how the type of rainfall

(i.e., orographic, frontal, and convectional) is related to the nature of location. (a)

•2.3.8 Explain how wind systems and precipitation are related. (k)

Types of Rain

• Three types of rainfall:1. Relief Rain2. Convectional 3. Frontal / Cyclonic Rain

Relief Rainfall• Stage 1.

Warm wet air is forced to rise over high land.

• Stage 2.As the air rises it cools & condenses. Clouds form & precipitation occurs.

• Stage 3.The drier air descends & warms.

• Stage 4.Any moisture in the air (e.g. cloud) evaporates

Convectional Rainfall

•Stage 1The sun heats the ground & warm air rises.

•Stage 2As the air rises it cools & water vapour condenses to form clouds.

Convectional Rainfall•Stage 3. When the

condensation point is reached large cumulonimbus clouds are formed.

•Stage 4. Heavy rain storms occur with thunder & lightening due to the electrical charge created by unstable conditions.

Frontal / Cyclonic Rainfall

•Stage 1 An area of warm air meets an area of cold air.

•Stage 2. The warm air is forced over the cold air

•Stage 3. Where the air meets the warm air is cooled & water vapour condenses.

•Stage 4.Clouds form & precipitation occurs

http://www.curriculumbits.com/prodimages/details/geography/types-of-rainfall.html

Part 2: Ocean Currents Outcomes•In this lesson you will learn to... •2.4.1 Define the term ocean current. (k) •2.4.2 Analyze how ocean currents can

create different climatic conditions for two coastal locations on the same latitude. (a)

Ocean Currents

•1. Permanent or semi-permanent horizontal movement of surface water (the top 100m)

•It is unusually cold or hot, when compared with the surrounding water

•2. Caused by and shaped by,▫prevailing winds, ▫variations in temperature ▫density of water▫Coriolis force

Warm and Cold Currents• Cold ocean currents: move water

towards the equator.

▫ For example the Humbolt or Peru Current carries cold water from Antarctica toward the equator (along the South American coast). Can you find it on page 60?

▫ Another example is the Labrador Current which carries cold water from the Arctic Ocean down along the Labrador coast towards the Grand Banks. Can you find it on page 60?

Cold Ocean Currents…Practical Examples• Mary’s Harbour on the

coast of Labrador is affected by the Labrador Current which gives Mary's Harbour cool summer temperatures & surprising little precipitation for a location right on the oceans edge.

• Drying & cooling effect to maritime climate

Newfoundland Coast

•LC brings both cool water & air south from the Arctic

•When this meets the warm Gulf Stream, flowing north from the equator, fog forms along our coast

•There is a frontal effect created off our coast contributing both to our precipitation & wet / foggy weather conditions

Practical Examples•Newfoundland's south

coast has ice-free ports year-long while its north coast has heavy ice for several months.

•The difference in latitude is not enough to explain this difference in ice.

•Can you explain it with ocean currents?

Warm and Cold Currents• Warm ocean currents: Move water away

from warm equatorial regions.

▫ For example the Gulf Stream moves warm water from the Gulf of Mexico northeast toward England. Can you find it on page 60?

▫ Another good example is the Japanese current which moves warm water from Japan northeast towards Vancouver. Can you find it on page 60?

Ocean Currents & the Affect on Climate

•Affect of cold ocean currents▫Cools the summer temperature; ▫Reduces precipitation; cooler air holds less

moisture. ▫Maritime Climate

Ocean Currents & the Affect on Climate

•Affect of warm ocean currents ▫Warms the winter temperature; ▫Increases precipitation; warmer air holds

more moisture. ▫El Nino

•http://www.cdli.ca/courses/geog3202/unit02_org03_ilo02/b_activity.html