Miss Nelson

SCIENCE ~ CHAPTER 9

CLIMATE

What Causes Climate?

SECTION 1

Differences in pressure, heat, air movement, and humidity result

in changes of weather.

ANTICIPATORY SET

S 6.4.a –Students know the sun is the major source of energy for phenomena on Earth’s surface; it powers winds, ocean currents, and the water cycle

S 6.4.e –Students know differences in pressure, heat, air movement, and humidity result in change in weather

STANDARDS

The main factors that influence temperature are:

LatitudeAltitudeDistance from larger bodies of

waterOcean currents

THE BIG IDEA

Climate – the average long-term conditions of temperature, precipitations, winds, and clouds in an area

Microclimate – climate conditions within a small area that diff er from those in the surrounding area

Marine climate – the climate of some coastal regions, with relatively warm winters and cool summers

Continental climate – the climate of the centers of continents, with cold winters and warm or hot summers

KEY TERMS

Ocean current – a large stream of moving water that flows through the ocean in a regular pattern

Windward – the side of a mountain range that faces the oncoming wind

Leeward – he side of a mountain range that faces away from the oncoming wind

Monsoon – sea or land breeze over a large region that changes direction with the seasons

KEY TERMS

Scientists use two main factors to determine climate:

Precipitationtemperature

WHAT CAUSES CLIMATE?

Main factors that influence temperature are:

LatitudeAltitudeDistance from large bodies of water

Ocean currents

FACTORS AFFECTING TEMPERATURE

Review World Temperature Zones for the effects of latitude on temperature

LATITUDE

In the case of high mountains, altitude is a more important climate factor than latitude

As a result, highland areas everywhere have cool climates, no matter what their latitude

ALTITUDE

Oceans or large lakes can affect temperature

Oceans make the temperatures of nearby land less extreme (than they would be without the ocean)

Water heats up more slowly than land

Water cools down more slowly than land

Winds off the ocean often prevent extremes of hot and cold in coastal regions

DISTANCE FROM LARGE BODIES OF WATER

Marine climate are often influenced by ocean currents

Some warm surface currents move heat from the tropics toward the poles

Affects climate as the warm ocean water warms the air above it

The best warm water current is the Gulf Stream

View the Gulf Stream currents on page 349 of your textbook

OCEAN CURRENTS

Read Factors Affecting Temperature on pages 347 – 349 of your textbook

FACTORS AFFECTING TEMPERATURE

The main factors that affect precipitation are:

Prevailing windsThe presence of mountains

Seasonal winds

FACTORS AFFECTING PRECIPITATION

Weather patterns depend on the movement of huge air masses

These air masses are move from place to place by prevailing winds

The directional winds that usually blow in a region

PREVAILING WINDS

Air masses can be warm or cool, dry or humid

The amount of water vapor in the air mass influences how much rain or snow will fall

The amount of water vapor in the prevailing wind also depends on where the winds come fromWinds that blow inland from oceans or large lakes carry more water vapor than winds that blow from over land

PREVAILING WINDS

A mountain range in the path of prevailing winds can also influence where precipitation falls

When humid winds blow from the ocean to the coastal mountains, they are forced to rise

As they rise the air cools and its vapor condenses, forming clouds

MOUNTAIN RANGES

The Sierra Nevada mountains have a major effect on California’s climate

Extremely dry areas (such as Death Valley) are located on the leeward side of the mountains

View Figure 4 on pages 350 – 351 of your textbook

MOUNTAIN RANGES

A seasonal change in wind patterns can affect precipitation

Sea and land breezes over a large region that change direction with the seasons are called monsoons

Thailand and parts of India receive much of their rain from the summer monsoons

Monsoon winds also bring rain to coast areas in West Africa and northeastern South America

SEASONAL WINDS

Regions affected by monsoons receive very little rain in winter

In the winter, the land cools and becomes colder than the ocean

A “land breeze” blows from the land to the ocean, which carries little moisture

SEASONAL WINDS

The Santa Ana winds are hot, dry winds that often blow in Southern California during fall and early winter

Cool air from the desert blows toward the coast

As air flows down the mountain, it is compressed and warms up

The humidity of the air drops and vegetation dries out, creating a potential fire hazard

SEASONAL WINDS

Read Factors Affecting Precipitation on pages 350 – 351 of your textbook

FACTORS AFFECTING PRECIPITATION

The seasons are caused by the tilt of Earth’s axis as Earth travels around the sun

THE SEASONS

The axis is an imaginary line through Earth’s center that passes through both poles

The axis ALWAYS points in the same direction

The north end of the axis is pointed away from the sun for part of the year, and toward the sun for another part of the year

View Figure 7 on page 353 of your textbook

TILTED AXIS

In June the northern hemisphere receives radiation (heat) from the sun at a more direct angle

In December, the north end of Earth’s axis is tiled away from the sun

EFFECT OF THE TILTED AXIS

Read The Seasons on page 352 of your textbook

THE SEASONS

Define climate.

What are the factors that affect temperature?

CHECK FOR UNDERSTANDING

Define climate.Cimate refers to the long-term, average conditions of temperature, precipitation, winds, and clouds in an area.

What are the factors that affect temperature?The facts that affect temperature are latitude, altitude, distance from large bodies of water, and ocean currents.

CHECK FOR UNDERSTANDING

Complete the Modeling, Guided Practice, and Independent Practice

Sections of your Climate 9-1 Worksheet.

MODELING / GUIDED / INDEPENDENT