Seasons and Weather

Chapter 3, Section 1

Seasons

Earth is tilted at a 23.5˚ anglecauses different areas to get direct sun rays for different

amounts of time creating seasons

Seasons

Tropic of Cancer and Tropic of Capricorn are the farthest points north and south where the sun shines directly overhead at noon – solsticebeginning of winter or

summer

Summer Solstice

Winter Solstice

Equinox

Seasons

Equinox – twice a year when the days and nights are the same all over the worldbeginning of spring and fall

Weather - immediate condition of the atmosphere at a specific location and time

climate – general weather conditions over a long period of time

What causes weather?water vapor causes precipitationcloud cover holds water vapor

What causes weather?

landforms and bodies of water water heats and cools slowly

land heats and cools quickly

What causes weather?

elevation higher elevation = thinner air (doesn’t hold moisture)

What causes weather?

air movement wind moves air and moisture causes rapid weather changes

Precipitation

Warm air rises air cools clouds form water vapor builds up pressure releases and it rains

3 types

Convectional

Hot, moist climateHeat air in the morning, clouds form by

afternoon and rain falls

Orographic - mountains

Windward side (wet side) of mountain blocks air and forces it up

Leeward side (dry side) has a rain shadow (very little precipitation)

Frontal

Mid-latitudeBoundary between 2 air masses with

different temperaturesCold air pushes warm air up =

precipitation

Weather Extremes

blizzards – heavy snowstorm with winds > 35 mph

drought – long period of time with little or no rain

Floods – water spreads over usually dry land

Flood plain – when water spills out of a river into surrounding area

Hurricanes

• Hurricane winds also cause storm surges (water flooding in from the ocean) 15 feet or more.

• This is what did the most damage to Galveston in the 1900 hurricane. The highest point on the island was only 8.5 feet. The storm surge was over 15 feet.

• 6,000 to 12,000 people died and the clean up was horiffic.

• To prevent such damage again, a 17 foot wall was built and the entire city was raised 17 feet

Damage to Galveston after the 1900 hurricane

Galveston Seawall

Raising Galveston

• They moved about 440 million cubic feet of sand into the city.

• Everything was raised between a few inches to 17 feet, including the 6 million pound St. Patrick’s Church.

Galveston was known as the New York of the South. It was the largest, most developed, and most modern city in Texas. Houston was a backwater, a “country-bumpkin” town compared to Galveston. After the 1900 hurricane, though, development shifted to Houston and Galveston was forever left behind.

Hurricane Rita

Katrina

IKE

Blizzards

• Massive snowstorm with high winds

Drought

• Long period with little or no rain

• Damages crops, plants, and wildlife

• Can also cause massive wind erosion, as in the Dust Bowl of the early 1930’s.

Blizzards

• Massive snowstorm with high winds

In South Dakota

Floods

• Lots of rain or runoff causes rivers and streams to overflow their banks