Select all of the true statements about surface currents. a. they form gyres. b. they transport heat across earth's surface. c. they are known as "thermohaline circulation." d. they are caused by wind and earth's rotation. e. they are driven by density differences in the water. f. they take hundreds to thousands of years to complete a cycle.

When does a spring tide occur? question 9 options: they occur when the sun, moon, and earth are aligned. in spite of their name, these tides occur twice a year in the spring and fall. they occur on the date of the vernal equinox each year, no matter what stage the moon is in. this is why they are called spring tides. they occur when the sun, moon, and earth are at 45-degree angles from each other. this happens once every spring. they occur when the sun, moon, and earth are aligned. in spite of their name, these tides occur all year long.