Climate is defined by the long-term weather patterns and temperature of a given area. The major factor influencing climate is the latitude of the region. The weather around the equator is fairly steady, temperature only varying slightly. Further north or south from the equator the climate may vary dramatically. The tilt of the Earth's axis helps create the seasons.
Ocean currents are created by four primary sources. Water is heated as it absorbs energy from the sun. Winds pull on the surface of water, causing it to slowly move. Gravity pulls on the water as well, tugging it toward the center of the planet. The Coriolis Effect, caused by the Earth's rotation, also pulls on ocean water -- to the right in the northern hemisphere, to the left in the southern. These four factors combine, creating a pulling effect that slowly moves water across the planet. These currents affect climate by pulling warm water from the equator and cold water from the poles. An example is the Gulf Stream, which brings warm weather from the equator to Europe, keeping the continent warmer than it would be otherwise.
Wind is created by differences in atmospheric pressure. Air moves toward the area with the lowest pressure. The prevailing wind of an area can greatly influence local climate. Weather patterns are vastly different depending upon their origin. Air pulled from the poles is normally colder than weather originating from the equator. The amount of moisture wind travels over also affects climate. Air from the desert brings drier weather than air from the Great Lakes. Over time, prevailing wind and weather patterns greatly alter the climate of a region.
A shift in an ocean current or prevailing wind can alter the climate of a region over time. A phenomenon in the Western Hemisphere is El Nino. Every few years the trade winds around the Indian subcontinent do not reverse as they normally would. This causes the temperature of the Pacific Ocean to rise, changing weather patterns and affecting ocean levels. The climate of Earth is still not fully understood by scientists. The subject has attracted greater attention lately as weather patterns are less stable and predictable, becoming part of the debate on climate change. Climatologists continue studying the effect of all factors on climate. Understanding the possible effects of humans is important in preserving the environment that supports their existence.