Science Review 2 nd Nine Weeks Chapters 5-7 Atmosphere and Weather and 8-10 Earth, Sun, and Moon Haynesfield Elementary 6 th Grade

What causes the seasons to change?  The Earth’s tilt  When the Northern Hemisphere is pointed away from the sun, it’s winter.  When the Northern Hemisphere is pointed toward the sun, it’s summer.  Equinox happens 2 times a year.

What about Seasons?? During summer, the days are longer! KNOW THIS CHART!

Rotation v Revolution  A day is the amount of time it takes for Earth to rotate on its axis.  Earth’s rotation causes day and night.  Earth rotates counterclockwise.  The moon’s rotation is equal to its revolution, which is why we only see one side of the moon.  A year is the amount of time it takes for Earth to revolve around the sun one time. (approx. 365 days)  Both the moon’s rotation and revolution are about a month (27 days).  A lunar cycle is a month

So…why does the moon look different?  Because of the changing position of the moon in relation to Earth and the sun, the moon looks different.  MUST know the phases and their names AND how long between phases!  The moon rotates counterclockwise

Tides  Tides are determined by the moon’s gravitational pull  High tides occur on the part of Earth that is closest to the moon and farthest from the moon.  Spring tides are stronger than Neap tides and occur during a full moon or new moon. Highest tides and lowest tides.  Neap tides are not as strong. When the sun, Earth, and moon form a right angle and occur during the first quarter or third quarter moon phases.  Spring tides occur when the sun, Earth, and moon are in a straight line.

Ocean Currents  Surface Currents: The wind causes Earth’s surface currents  The largest surface current is the Gulf Stream  This current causes it to be warmer in Europe than it “should” be  Currents circulate heat away from the equator

Atmospheric Layers  Troposphere: Where we live  Stratosphere  Mesosphere: coldest layer  Thermosphere: temp is high but it’s not hot  The atmosphere acts as a “blanket” for Earth, trapping thermal energy (heat) inside.  What traps the heat? Carbon dioxide and water vapor (remember the greenhouse effect??)

Sun’s energy drives….  Temperature : The sun heats and cools the earth  Weather  Wind: The uneven heating of the earth’s surface  The Water Cycle: Causes evaporation  Creates high and low pressure systems

Air Masses  A warm air mass over water will bring rainfall.  There are four air masses associated with U.S. weather: Maritime Polar, Maritime Tropical, Continental Polar, and Continental Tropical  Maritime air masses form over water, which is why they bring precipitation.  Continental air masses form over land.

Air Masses  A warm air mass over an ocean would create rainfall. Why?

Cold Front  When cold air moves under warm air and pushes it up  Brings thunderstorms, heavy rain, or snow  Cooler weather follows

Warm Front  Warm air moves over colder, denser air  Gradually replaces the cold air  Bring drizzly rain and are followed by clear, warm weather

High or Low Pressure?  Low pressure, also called cyclones, brings clouds and rain.  Low Pressure System: This is a region of relatively lower pressure. There will be rising air and thus often there will also be clouds and precipitation. Low pressure is colored in red. The choice of the color red has nothing to do with temperature. While it is typically cooler under a low due to the the cooling from cloud cover as well as rain or snow, temperatures can vary between being mild to being very cold.  High pressure, also called anticyclones, brings warm, dry, clear weather.  High Pressure System: This is a region of relatively higher pressure. There will often be sinking air and thus stable weather. Sunny weather will often occur under high pressure. High pressure is colored in blue. The choice of the color blue has nothing to do with temperature. High pressures can bring with warm or cold weather depending on the type of high pressure it is.

Convection and Conduction  Heat travels by convection through wind.  Convection currents carry warm and cold air.  Warm air rises and expands.  Cold air “sinks and shrinks”  Heat travels by conduction through materials.  Examples: Stove, hot car door, hot water