Seasons and Seasons and WeatherWeather

Chapter 3:Chapter 3:

Section 1 Section 1

A Human PerspectiveA Human Perspective• The smell of thousands of decaying corpses hung in

the air in what was once the thriving seaport of Galveston, Texas. The day before, winds estimated at 130 miles per hour roared through the city. A Storm surge of seawater more than 15 feet high pushed a wall of debris across the island of Galveston. Through this turmoil, Isaac Cline’s family huddled in their home. A trolley trestle rammed the house until at last it collapsed, and the waves poured in. Cline survived, but some of his family did not. With a toll of 8,000 human lives, the “Great Galveston Hurricane” would be the deadliest hurricane to hit the United States. The storm date was August 8, 1900.

SeasonsSeasons• The seasons are related to the

earth’s tilts and revolution.• Some locations receive more direct

sun rays because of the earth’s tilt.• Revolution: one complete orbit

around the sun. (365 ¼ days)• Rotation: earth makes one rotation

every 24 hrs.

The causes of the changing season The causes of the changing season on the earth?on the earth?

• Solstice occur around December 22 & 23 & around June 21 or 22.

• Summer, sun hit directly at Tropic of Cancer.

• Winter, sun hit directly at the Tropic of Capricorn.

• 24 hrs. of light or darkness in Arctic Circle or Antarctic Circle.

• Equinoxes is Latin for “equal night”

• Poles are not pointed toward or away from the sun & both hemispheres receive exactly 12 hrs of sunlight.

• Spring, March 21, is called Vernal Equinox. Northern Hemisphere.

• Fall, September 21, is called Autumnal Equinox. Northern Hemisphere.

WeatherWeather• Weather and climate are often

confused.• Weather is the condition of the

atmosphere at a particular location and time.

• Climate is the term for weather conditions at a particular location over a long period of time.

What causes the weather?What causes the weather?• The amount of solar energy received by an area

by its location to the earth position and sun.• Water Vapor: it determine whether there will be

precipitation. (rain, sleet, snow, or hail)• Cloud cover will hold water vapor.• Landforms & bodies of water: Water heats

slowly but can retain heat, & land heat rapidly but loses heat quickly.

• Elevation: As elevation increases, the air becomes thinner and loses is ability to hold moisture.

• Air movement: winds move the air and the solar energy and moisture that it holds.

Precipitation: water vapor in Precipitation: water vapor in the air (rain)the air (rain)

• Convectional: hot climates, the sun heats the air, and warm air rises

• Orographic: Associated in mts. Areas. Mountain block the passage of the air and cause it to rise. Windward receives the rain & on the leeward side is called rain shadow & does not received any water only dry air.

• Frontal: Mid-Latitude,cold dense air pushes up warm, light air causing precipitation.

ConvectionalConvectional

                                                 

FrontalFrontal

Weather Extremes: as air moves across Weather Extremes: as air moves across the earth, warm and cool air collides the earth, warm and cool air collides

with each other and they create with each other and they create weather.weather.

•Hurricanes•Tornadoes•Blizzards•Droughts•Floods

HurricanesHurricanes• They are storms that form

over warm, tropical ocean water.

• Different names:• In Asia:typhoons, • Tropical cyclones• Australia: willy-willies• Philippines: baguios• Mexico:Chubascos• Different categories.• Stage 1 is just above 75

miles to stage 5, over 150 miles.

• Danger: storm surges, flooding & high winds.

• 25 to 30 per yr., but only 3 to 6 make landfall.

TornadoesTornadoes• Or a twister, is a

powerful funnel-shaped column of spiraling air.

• They form quickly & without warning.

• Born from strong thunderstorms, winds swirl counter-clockwise, & winds may reach speed of 300 miles per hour.

• Usually small diameter & will last only a few minutes, but they have been know to be as wide as a mile & last for hours.

• 700 tornadoes each yr.

• This is the oldest known photo of a tornado. It was taken on August 28, 1884 near Howard, South Dakota. The name of the photographer is not known.

BlizzardsBlizzards• Is a heavy snowstorm

with winds of more than 35 miles per hour and reduced visibility.

• Some areas because of their location will received as much as 37.5 feet of snow per year.

DroughtsDroughts• A long period of time

without rain or with very minimal rainfall.

• Makes in hard on crops & results in reduced levels in water storage.

• 1930s, the Great Plains were known as “Dust Bowl” as 150,000 square-mile were hit with dust storms.

FloodsFloods• When water spreads

over land not normally covered with water.

• Melting snow or rainwater will fill rivers until they reach a flood stage.

• After a river cannot take water any more it will flows into surround areas called floodplain.