Adopt-A-Drifter Program Adopt-A-Drifter Program Lesson 2: ClimographsLesson 2: Climographs

Ocean Surface Ocean Surface Currents and Currents and

ClimateClimate

What is climate?What is climate?

• The The long-term averagelong-term average of conditions of conditions in the atmosphere, ocean, ice sheets, in the atmosphere, ocean, ice sheets, and sea ice described by statistics, and sea ice described by statistics, such as means and extremes. such as means and extremes.

What is weather?What is weather?• The The specificspecific conditions conditions

of the atmosphere of the atmosphere at a at a particular place and timeparticular place and time, ,

measured in terms of measured in terms of variables that includevariables that include temperature, precipitation, temperature, precipitation, cloudiness, humidity, cloudiness, humidity, air pressure, and wind.air pressure, and wind.

What are ocean surface What are ocean surface currents?currents?

• The surface currents of the world’s The surface currents of the world’s ocean are driven mainly by wind and ocean are driven mainly by wind and move in circular patterns following the move in circular patterns following the major wind belts of the globe. major wind belts of the globe.

(photo credit: Rick Lumpkin,(photo credit: Rick Lumpkin,www.adp.noaa.govwww.adp.noaa.gov))

How do ocean currents How do ocean currents circulate water around the circulate water around the earth?earth?

• In general, currents carry warm water from In general, currents carry warm water from the tropics toward the poles and bring cold the tropics toward the poles and bring cold water back toward the equator.water back toward the equator.

(photo credit:(photo credit:

www.geomorphology.org.uk/weather)www.geomorphology.org.uk/weather)

How do currents affect the How do currents affect the surrounding air?surrounding air?

• A surface current warms or cools the A surface current warms or cools the air above it, influencing the climate air above it, influencing the climate of the land near the coast.of the land near the coast.

Warm Water CurrentsWarm Water Currents

• Winds pick up moisture as they blow Winds pick up moisture as they blow across warm water currents. This across warm water currents. This often brings mild, rainy weather to often brings mild, rainy weather to the coastal regions. the coastal regions.

(photo credit: Amanda Laurier)(photo credit: Amanda Laurier)

Warm Water CurrentsWarm Water Currents

• Example: The Gulf StreamExample: The Gulf Stream

(photo credit:(photo credit:

www.geomorphology.org.uk)www.geomorphology.org.uk)

Warm Water CurrentsWarm Water Currents

• The Gulf Stream brings relatively warmer The Gulf Stream brings relatively warmer temperatures to western Ireland and temperatures to western Ireland and Great Britain, resulting in a subtropical Great Britain, resulting in a subtropical climate with mild winters.climate with mild winters.

Logan Botanic Garden,Logan Botanic Garden,

ScotlandScotland

(photo credit: Archie Miles)(photo credit: Archie Miles)

Cold Water CurrentsCold Water Currents

• Cold water currents cool the air above Cold water currents cool the air above them and since cold air has less of an them and since cold air has less of an ability to take up moisture than warm ability to take up moisture than warm air, these currents tend to bring cool, air, these currents tend to bring cool, dry weather to adjacent land areas. dry weather to adjacent land areas.

• Fog is often found along the land-sea Fog is often found along the land-sea borders where cold ocean currents borders where cold ocean currents exist. exist.

Cold Water CurrentsCold Water Currents

• Example: Atacama Desert, Chile, South Example: Atacama Desert, Chile, South AmericaAmerica

Cold ocean currents keep clouds and fog just off the Cold ocean currents keep clouds and fog just off the coast, making it one of the driest places on earth.coast, making it one of the driest places on earth.

(photo credit: Mary Cook) (photo credit: Mary Cook)