Climate and Climate Change
Climate
- Climate is the _____________ _______________ __________________ in an area over a long period of time.
- Climate is determined by a variety of factors that include ______________, ______________________
circulation patterns, ______________ circulation patterns, the local ______________ of an area, solar activity,
and _________________ activity.
- The most important of these factors is distance from the ___________________.
Latitude
- Latitude is the distance _______ or _______ from the equator and is expressed in ____________.
- The equator is located at ___ latitude. The most northerly latitude is the _________ ________, at ___ north,
whereas the most southerly latitude is the _______ ______, at ____ south.
- Latitude ______________ affects climate because the amount of _________ _________ an area of the Earth
receives depends on its latitude.
Low Latitudes
- More solar energy falls on areas near the ____________ than on areas closer to the poles.
The incoming solar energy is ____________________ on a small surface at the equator.
In regions _______ the equator, night and day are both about ___ hours long throughout the year.
In addition, temperatures are _______ year-round, and there are no _____________ or ______________.
High Latitudes
- In regions closer to the _________, the sun is __________ in the sky, reducing the amount of energy arriving at
the _____________.
- In the northern and southern latitudes, sunlight hits the Earth at an _____________ _________ and spreads
over a larger ___________ ______ than it does at the equator.
- Yearly _____________ temperatures near the poles are therefore ___________ than they are at the equator.
- The _______ of daylight also vary. At ____ north and south latitude, there is as much as ___ hours of daylight
each day during the summer and as little as ___ hours of sunlight each day in the winter.
- Near the poles, the sun _____ for only a few hours each day during the summer and _____ for only a few hours
each day during the winter.
- Thus, the yearly __________________ ________ near the poles is very large.
Atmospheric Circulation
- Three important _____________of air illustrate how air __________________ affects climate.
- Cold air ________ because it is ___________ than warm air. As the air ________, it compresses and _________.
- Warm air ________. It ___________ and ________ as it rises.
- Warm air can hold more __________ _________ than cold air can. Therefore, when warm air________, the
water vapor it contains may ___________________ into liquid __________ to form rain, snow, or fog.
- Solar energy heats the ____________, which _________ the air above it. This warm air _________, and cooler
air moves in to _____________ it. This movement of air within the atmosphere is called __________.
- Because the Earth ____________, and because different latitudes receive __________________ amounts of
solar energy, a pattern of global atmospheric _________________ results.
- This circulation pattern determines Earth’s _______________ patterns.
- For example, the ______________ solar energy striking the Earth’s surface at the ________________ causes the
surface as well as the _____ above the equator to become very _________.
- This warm air can hold _________ _____________ of water vapor. But as this warm air ______ and _______, its
ability to hold water is ____________.
- As a result, areas near the equator receive large amounts of ________.
Global Circulation Patterns
- Cool air normally _______, but cool air over the equator __________ descend because hot air is _________ ___
below it. This _______ _____ is forced away from the equators toward the _________ and _________ Poles
where it accumulates at about ___ north latitude and ___ south latitude.
- Some of the air _________ back to the Earth’s surface and becomes ____________ as it descends. This warm,
____ _____ then moves across the surface and causes water to ______________ from the land below, creating
____ conditions.
- Air descending at the ____ north and ____ south latitude either moves __________ the equator or flows
_________ the poles. Air moving toward the equator _________ while it is near the Earth’s surface.
- At about ____ north and ____ south latitudes, this air ___________ with cold air traveling from the poles.
- The warm air _______, and most of this uplifted air is forced _________ the poles. Cold, dry air ___________ at
the poles, which are essentially very cold _______________.
Prevailing Winds
- Winds that blow predominantly in ______ _______________ throughout the year are called _______________
__________.
- Because of the _________________ of the Earth, these winds ___ ______ blow directly northward or
southward. Instead, they are ______________ to the _________ in the Northern Hemisphere and to the
_______ in the Southern Hemisphere.
- Prevailing winds known as the _________________ are produced between ____ and ____ north latitude and
____ and ____ south latitude.
- In the Northern Hemisphere, these _______________ are _______________ winds, and in the Southern Hemisphere, these winds are _________________ winds.
- The polar ________________ blow from the poles to ____ north and south latitude.
Oceanic Circulation
- Ocean currents have a _________ _________ on climate because water holds large amounts of _______.
- The movement of surface ocean currents is caused mostly by _______ and the rotation of the ________.
- These surface currents _______________ warm and cool masses of water around the world and in doing so,
they affect the ________ in many parts of the world.
El Niño–Southern Oscillation
- El Niño is the ______ phase of the El Niño–Southern Oscillation. It is the ________________ occurrence in the
eastern Pacific Ocean in which the surface-water temperature becomes unusually _______.
- During El Niño, winds in the western ___________ Ocean, which are usually weak, strengthen and push warm
water eastward.
- Rainfall follows this warm water _____________ and produces increased rainfall in the southern half on the
U.S., but drought in _________________
- La Niña is the ______ phase of the El Niño–Southern oscillation. It is the _______________- occurrence in the
eastern Pacific Ocean in which the surface water temperature becomes unusually ________.
- El Niño and La Niña are _____________ phases of the El Niño–Southern Oscillation (ENSO) cycle.
Pacific Decadal Oscillation
- The Pacific Decadal Oscillation (PDO) is a long-term, ___ to ___ year change in the location of ______ and _____
water masses in the Pacific Ocean.
- PDO influences the climate in the northern ______________ Ocean and North America.
- It affects ocean ___________ temperatures, _____ temperatures, and __________________ patterns.
Topography
- Height above sea level (______________) has an important effect on climate. Temperatures _______ by about
6°C (about ____) for every ___________increase in elevation.
- Mountain ranges also influence the distribution of ____________________. For example, _______ _____from
the ocean blows _______, hits the mountains, and _______. As the air rises, it _______, causing it to ______ on
the _____________ side of the mountain. When the air reaches the eastern side of the mountain it is ______.
This effect is known as a ________ _________________.
Other Influences on Earth’s Climate
- Both the sun and _____________ _____________ influence Earth’s climate.
- At a solar ______________, the sun emits an ________________ amount of ultraviolet (UV) radiation. UV
radiation produces more ________, which warms the stratosphere.
- The increased solar radiation can also warm the ________ ____________________ and surface of the Earth a
little.
- In large-scale volcanic eruptions, ________ _______________ gas can reach the upper atmosphere.
- The ________ ____________, which can remain in the atmosphere for up to __ __________, reacts with smaller
amounts of __________ __________and dust in the stratosphere.
- This reaction forms a bright layer of ________ that reflects enough sunlight to cause the global temperature to
_____________.
Seasonal Changes in Climate
- The seasons result from the _____ of the Earth’s axis, which is about 23.5° relative to the plane of its orbit.
- Because of this tilt the ________ at which the sun’s rays __________ the Earth changes as the Earth moves
around the sun.
- During summer in the Northern Hemisphere, the Northern Hemisphere tilts _____________ the sun and
receives __________ sunlight. The number of hours of daylight is __________ in the summer. Therefore, the
amount of time available for the sun to heat the Earth becomes ______________.
- During summer in the Northern Hemisphere, the Southern Hemisphere tilts _______ from the sun and receives
________ direct sunlight. But, during the summer in the Southern Hemisphere, the situation is
______________.