Seasons and Weather

• Earth’s Tilt– As the Earth revolves around the sun, it is

tilted at a 23.5 degree angle in relation to the sun

– Different parts of the earth receive the direct rays of the sun for more hours of the day. This causes the changes in the seasons

Seasons

– The Tropic of Cancer and the Tropic of Capricorn mark the points farthest north and south that the sun’s rays shines directly overhead at noon

– Solstice- day that occurs, first day of summer and winter

– Equinox- twice a year, the days and nights all over the world are equal lengths

Weather

• Weather- the condition of the atmosphere at a particular location and time

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

What causes weather?

– Solar energy from the sun– Water vapor- whether there will be

precipitation or not– Cloud cover- clouds may hold water vapor– Landforms and bodies of water– Elevation– Air movement

Precipitation

• Depends on amount of water vapor in the air

Convectional

–precipitation occurs in hot, moist climate where the sun quickly heats the air

Orographic

• Falls on windward side of hills or mountains that block moist air and force it upward. The air cools and rain or snow falls. The land on the leeward side is called a rain shadow because it gets little rain from the descending day air

Frontal Movement

–causes rain in the mid- latitudes

Weather Extremes• Hurricanes

– Sometimes called typhoons– Storms that form over warm, tropical ocean

waters– Eye- calm center of hurricane – Can be up to 200 miles per hour and 500

miles wide

Tornadoes

• Form quickly and without warning

• Powerful funnel-shaped column of air

• Winds may reach 300 miles per hour

• Blizzards -Heavy snowstorm with winds of more that 35 miles per hour

• Droughts- long period of time without rain or with very little rain

• Floods- when water spreads over land not normally covered with water

LACEMOPS

• Factors Affecting Climate

Weather vs. Climate

• Weather: atmospheric conditions right now• Climate: pattern of weather over a long

period of time for a specific location

L- Latitude

• the further from the equator, the colder it will be; sun’s rays hit directly only between 23.5° S and 23.5°N (Tropic of Cancer and Tropic of Capricorn)

A- Air Masses

• Cold air from polar regions; warm air from the tropics

C- Continentality

• water moderates climate; water takes longer to heat and cool than land; the further from a large body of water that a place is, the more the temperature will fluctuate

E- Elevation

• increase in altitude means a decrease in temperature; for every 1000 ft increase in elevation, there is a 3.5° F decrease in temperature

M- Mountain Barrier

• stop wind and storms; also create rain shadow on the leeward side of a mountain range (lots of precipitation close to body of water, very dry on other side of mountain range)

O- Ocean Currents

• cold currents bring dry air; warm currents bring moist air

P- Pressure and Prevailing Winds

• High Pressure systems are heavy & cold; Low Pressure systems are light & warm (also see p. 54 in text for prevailing wind patterns)

S- Storms

when warm & old air masses collide, some sort of storm or precipitation is the outcome