Weather &

Climate

Unit 1

Chapter 2

A. Weather & Climate1. Weather - the condition of the bottom layer of the

earth’s atmosphere in one place over a short period of time

- temperature, moisture, precipitation, wind

2. Climate – the weather patterns in an area over a long period of time

***Usually described in Temperature & Precipitation****

- depends on elevation, latitude, location of nearby landforms & bodies of water, wind & ocean currents

*** Climate is what you expect, weather is what you get!!

Section 1: Weather & Climate

B. The Sun & the Earth1. The Greenhouse Effect

a. Enough solar radiation reaches earth’s surface to warm air & water

b. Atmosphere prevents heat from escaping back into space too fast (similar to glass walls &

roof on a greenhouse) – allows warmth for plants to grow

SECTION 1

Factors Affecting ClimateThe Sun’s Effect on Earth

The Sun’s energy reaches Earth

Half of the energy is reflected back into space or absorbed by the atmosphere.

The other half is absorbed by Earth’s surface and converted into heat energy.

The atmosphere traps this heat in a process called the greenhouse effect.

The greenhouse effect helps keep the planet warm.

c. Global Warming – a rise in earth’s temp. caused by amts of CO2 & other

substances – earth’s atmosphere traps heat from sun & reflects it back to earth. As gasses build up in atm., more heat trapped, global temps rise.

- occurs naturally or by human action

* Global Warming could…

- partially melt ice caps causing rise in ocean level + flooding of low-lying

areas

- increase precipitation in some areas/decrease it in others

SECTION 1

The Solar System

Sun

Mercury

Venus

Earth

Mars

Uranus

Neptune

Pluto

Jupiter Saturn

2. Rotation & Revolution

a. Rotation = the spinning motion of the earth (like a top)

1) earth completes 1 rotation in 24 hrs

2) daytime – side that faces sun

3) nighttime – side facing away from sun

b. Revolution = 1 complete orbit of the earth around the sun

1) 1 revolution = 365 ¼ days

2) 4 x ¼ days = leap year

c. earth tilted on axis 23 ½º

1) “tropics” receive most direct sunlight

2) because of tilt, sunlight strikes diff. parts of earth more directly at diff times of yr.

3) when North Pole tilted toward sun, northern hemisphere receives most direct sunlight. When SP tilted toward sun, southern hemisphere receives most direct sun

4) these changes in SEASONS are solstices – either of the 2 times of yr when the sun appears directly

overhead at the Tropics of Cancer 23 ½ºN /Capricorn 23 ½ºS

5) Equinox – either of the 2 times/yr when day & night are of nearly = length everywhere on earth – sun appears directly overhead equator

Reason for the seasons

C. Precipitation

1. Precipitation vs. Humidity

a. Humidity – amt of water vapor in atmosphere

b. Precipitation – all forms of water that fall from the atmosphere to earth’s surface

1) forms as air temp changes

- warm, less-dense air absorbs more moisture than cool

- when air cools, can’t retain water vapor, so condenses as liquid cools

2) occurs when more water collects in clouds than they can hold

Forms of Precipitation

The Water Cycle

2. Types of Precipitation

a. Convectional Precipitation - occurs when hot, humid air rises from the earth’s surface,

cools, loses ability to hold water

- common at equator/tropics

b. Orographic Precipitation – occurs when warm, moist air forced upward over high

landforms (RAINSHADOW)

- common on seacoasts

- warm winds cool as they rise over mt clouds form, rain/snow

- air cool & dry on other side of mt

*** Cascades/Sierra Nevadas

Rainshadow

c. Frontal Precipitation – (most common) – occurs when 2 fronts (air masses of diff.

temps) meet. Warm air forced up by heavier, cooler air. As rising warm air cools, frontal precipitation forms

D. Influences on Climate (temp & precipitation)1. Latitude

a. sun’s rays fall most directly at or near equator, less direct toward poles – most place near eq. have warm climates – most near poles have colder climates

b. distance from eq. used to ÷ world into zones

1) Tropics = btwn 23 ½º N/S & the Eq.

- hot all yr

2) Temperate = 23 ½º N/S to 66 ½º N/S

- wide temp. range

3) Polar = 66 ½º N/S to NP/SP

- cool to bitterly cold

Climate Zones

2. Wind & Ocean Currents

a. Heat distributed via convection – the transfer of heat from one place to another

- warm gases/liquids are lighter/less dense than cooler

- warm gases/liquids rise, cooler sinks & displaces lighter/ warmer materials

- warm air/water flows from eq. to poles

- cold air/water flows toward eq.

b. Wind

1) winds move from high to low pressure. Mvmt of wind distributes sun’s heat over earth’s surface

- low pressure = rising warm air

- high pressure = falling cool air

2) Coriolis Effect – b/c earth rotates, winds are deflected (bend)

- NH = wind curves right

- SH = wind curves left

3) Wind Patterns: temp + pressure = pattern of prevailing (dominant) winds - Doldrums – area near equator

with calm/light breezes – warm air rising

- Horse Latitudes - ~ 30ºN/S with unpredictable winds – cool air sinks(Called Horse Lats b/c Spanish sailors sometimes had trouble getting enough wind to travel in that area, so when traveling to America, they threw their horses overboard to lighten ships/gain speed

- Trade Winds – btwn Horse-Equator

predictable winds blow toward Eq. from NE & SE(called trade winds b/c merchant trading ships depended on them to push heavy-laden ships across ocean)

Wind Currents

c. Ocean Currents – via convection, ocean waters help distribute heat: carry warm

water from tropics to poles or cool water from poles toward equator. ** wind + coriolis effect influences circular patterns of ocean currents

3. Nearby Bodies of Water

a. Land temps can change quickly & dramatically; water slower ; so, temps of lrg bodies of water affect surrounding climate

- winds that blow over water take on water temp

- thus, usually milder temps in coastal regions than at other areas in the

same latitude

- British Isles = mild climate

b. Areas away from influence of water, interior of continents, experience continental climates

4. Elevation

a. Affects climate more than its latitude position

b. As elevation increases, temps decrease

c. Can have snow-capped mts in the tropics

Mt. Kilimanjaro – Tanzania – latitude?

Look! Snow!

5. Nearby Landforms

a. no climate is ever uniform

b. Areas can be affected by landforms such as coastal mts, lakes, forests, & even a concentration of tall bldgs. Thus, city temps usually little warmer than surroundings

E. World Climate Regions – see chart

F. Climate Graphs

- consist of a line graph (temperature) & a bar graph (precipitation)

- Climate graphs present the Average Monthly Temperature and Average Monthly

Precipitation of a specific place

- Climate graphs also enable you to compare climates in different cities

Section 2: EcosystemsA. Introduction

1. Ecosystem – formed by the interaction of plant life, animal life, and the physical

environment in which they live

- can be affected by climate, sunlight, temperature, precipitation,

elevation, soil, landforms

- change in one aspect of an ecosys. can lead to changes in others (ex. Loss of

oak trees can affect squirrels)

2. Biome – term used to describe a major type of ecosystem that can be found in various regions throughout the world – a classification system

- see chart

• Another way to visualize major land biomes is to compare them based on their average temperature ranges and rainfall levels, which shows how these variables combine to create a range of climates

Tropical Rain Forrest

• Amazon River Basin• Congo River Basin• Dense multilayered canopy/broad leaf

evergreens

Mid Latitude Forest

• Much of U.S. • Deciduous- Loose their leaves

Coniferous Forest

• East Texas Piney Woods/ Colorado• Northern Forests/ Taiga- Cooler climates

Grasslands

• Temperate- Grasslands in the cooler part of the world. Great plains or prairies of U.S. and Steppes of Eurasia

• Tropical Grasslands- Equatorial grasslands called savannas

• Herbivores• Carnivores

Deserts

• Dry barren region with specialized plants and animals.

Tundra

• Temperatures always cool or cold• Small plants (specialized)• Permafrost