8.1 and 8.2 wind and ocean currents Flashcards
What causes global winds?
Uneven heating of Earth’s surface by the sun, pressure belts, convection, Coriolis effect,
How does air move according to pressure?
Air moves from areas of high pressure to areas of low pressure
What kind of pressure is created by cold air?
High pressure (molecules are closer together)
What kind of pressure is created by warm air?
Low pressure (molecules are more spread out)
Compare a valley breeze to a mountain breeze.
Valley breeze – during day, valley heats up, warm less dense air rises up toward mountains
Mountain breeze- at night, mountain cool quickly, cool dense air blows toward valley
Compare a sea breeze and a land breeze
Sea breeze – during day, land heats up faster than water, the cool more dense & high pressure air over water moves toward the warm less dense & low pressure air over land
Land breeze – at night land cools faster than water. The cool more dense & high pressure air over land moves toward the warm less dense & low pressure air over water
How does the jet stream affect our weather?
The polar jet stream bring cold arctic air to the US, and causes weather to move from west to east
How do the winds blow across the United States?
From west to east
Westerlies – wind that blows from the west to the east
What is convection? What is it caused by?
The movement of water or air caused by differences in density Density is affected by temperature and salinity (in water)
What does convection cause?
Movement of air & water due to differences in density, called convection currents
What is density?
Matter/mass per volume of matter or the amount of matter in a given amount of space (volume)
How does density affect convection of wind and water?
Dense matter sinks and less dense matter rises
How does salinity of ocean water affect the density of the water?
Salt increases density – more particles in the water
More salt = more dense
What is the Coriolis effect?
The curving of a moving objects path such as wind and water, due to the rotation of earth
How do currents move in the northern hemisphere? How do they move in the southern hemisphere?
Northern hemisphere = clockwise
Southern hemisphere = counterclockwise
How do surface currents move at the equator?
Straight East to west Due to surface winds
not curved or deflected (not affected by Coriolis Effect)
What causes the different movement in each hemisphere?
Coriolis effect
What causes/influences surface currents?
Global winds, continental deflection, Coriolis effect
What are deep ocean currents?
Stream like movement of ocean water far below the surface, along the ocean floor, formed by differences in density. - deep ocean currents are not affected by winds
What do currents transport?
Energy, water, gasses, dissolved solids, nutrients
Explain what an upwelling is. Why is it important?
wind-driven motion of dense, cooler, and usually nutrient rich water towards the ocean surface, replacing the warmer, usually nutrient-depleted surface water along the shoreline. Upwelling bring nutrients to shallow areas and shorelines
Describe the process that causes wind, which leads to surface currents.
Radiant energy from the sun warms Earth’s surface
Earth’s spherical shape & tilt on its axis contributes to the uneven heating of its surface
Earth warms the air above, causing the air to expand & become less dense.
Less dense air rises, forming an area of lower pressure at Earth’s surface.
As warm air rises at high altitudes, it cools and contracts
Cooling air becomes denser & begins to sink
The sinking air forms an area of higher pressure at Earth’s surface.
Air moves from an area of high pressure to an area of low pressure, forming wind
Wind pushes the surface of the water
What 3 factors most directly control surface currents?
Global winds
Coriolis Effect
Continental deflection
What is the MAIN cause of surface currents?
wind
When water density increases, what type of ocean currents form?
deep current
What two factors create deep ocean currents by increasing density?
Temperature decreasing
Salinity increasing
What two factors increase salinity in ocean water?
Freezing
Evaporation
What causes the Coriolis effect?
Rotation of Earth on its axis
What happens to a surface current when it meets a land mass?
It changes course, it is deflected
Warm surface currents are likely to form near the….
equator
cold surface currents are likely to form near the……
poles
What causes ocean currents near the equator to move east to west in direction?
Global winds - not affected by Coriolis Effect at the equator
What is the source of thermal energy that creates the uneven heating of Earth’s air and water?
Sun’s energy
