What else affects temperature (AND rainfall)? OCEAN CURRENTS
South Africa’s Ocean Currents Agulhas Current: Warm East coast Benguela Current: Cold West coast Agulhas Current South Africa Benguela Current
3. Where is this location. Cape Point. Where approx. 1 3. Where is this location? Cape Point. Where approx. 1.2km to the east, the two currents meet each other.
Global Ocean Currents 4. What do you notice? Cold always on west of continents, warm always on east – i.e. NOT only relevant for SA. Currents from poles are cold vs currents from tropics are warm.
Warm vs. Cold Currents Cool currents come from cold polar areas to the equator. Warm currents flow from hot equatorial areas to the poles. This aims to balance out differences in temperature. POLE EQUATOR 5. Origin influences whether hot or cold current. This is in order to balance out the variations in latitudinal temperature – so that poles don’t keep on getting colder and tropics don’t keep on getting hotter. POLE
Fish Hoek? Muizenberg? Camps Bay? More likely to swim at Muizenberg and Fish Hoek – they are closer to the warm Agulhas ocean current. Camps Bay?
Effects on Temperature Winds blow over the ocean onto land. Benguela: cold wind cools west coast Agulhas: warm wind warms east coast 7. Wind warms or cools the land depending on adjacent current. Warm wind: Cool wind:
Winds can carry water onto the land. Effects on Rainfall Winds can carry water onto the land. Low pressure (not a lot of air molecules) More space for water droplets to fit in High pressure (packed full with air molecules) Less space for water droplets to fit in WARM AIR COOL AIR
dry weather on west coast wet weather on east coast Effects on Rainfall Benguela: less water vapour dry weather on west coast Agulhas: more water vapour wet weather on east coast The cool Benguela is dense with air molecules – so less water vapour and brings dry weather to west coast, and vice versa with warm Agulhas bringing wet weather. Warm, humid wind: Cool, dry wind:
Class Exercise Write down how ocean currents will affect the temperature and rainfall of the following cities: a. Durban b. Port Nolloth c. East London d. Cape Town e. Kimberley (be careful!) Kimberley Port Nolloth Durban East London Cape Town