What is the weather forecast?

Condition of the atmosphere at a certain time and place Affected by the amount of water in the air Must understand water cycle to understand weather.

Review- 3 steps

Amount of water vapor in the air Water evaporates—becomes water vapor– humidity of air increases

Temp-affects the air’s ability to hold water vapor/humidity As temp increase, air’s ability hold water vapor increases

Amount of Water vapor in the air compared to the max amount of water vapor that the air can hold at a certain temp. Given as a percentage 100% = Saturated

Amount of water vapor More water vapor in air—higher relative humidity Same with each other

Temperature Temp-decreases then relative humidity will increase Opposite each other

Psychometer- measures this Less water vapor = less humidity

Gas changing to liquid Before it occurs air must be saturated Relative humidity = 100% Condensation is when saturated air cools

Temperature at which gas condenses into a liquid Air is saturated at this point Ice water- the ice causes the air to cool—result gas is sweating Have to have a surface for water to cool on (the glass)

Collection of millions of tiny water droplets or ice crystals They form as warm air rises and cools Saturated air cools-liquid or solid (depending on air temp.) Classified by form and by altitude

Puffy, white, flat bottoms are these -Can use imagination and create images Warm air rises cause these Fair weather When these get larger= thunderstorm cumulonimbus cloud– will produce rain

Are layers Cover large areas-not as high Block the sun Gentle lifting of large body of air into atmosphere

Nimbostratus- dark stratus- produce heavy/continuous rain Fog is a stratus cloud Formed near the ground

Thin, feathery, white clouds High altitude Made of ice crystals From when the wind is strong As they get thicker = weather is changing

Cirro- high clouds high altitude Ice crystals Alto- middle attitude Both water drops and ice crystals Low- water drops

Water in solid/liquid form falling to Earth 4 major types

Most common Clouds produce rain when Water drops in the clouds become a certain size Before hits ground has lost its size (100 times smaller than when formed)

Rain falls through a layer of freezing air Rain freezes in the air As fails water coats it Sometimes an updraft can send it into clouds again-another layer of ice coats it= bigger

Temp. are so cold that water vapor changes directly to a solid Can fall as single ice crystals Or can fall in clumps = snowflakes

Balls or lumps of ice that fall from clouds Form in cumulonimbus clouds Updrafts of air in the clouds carry raindrops high the clouds, the raindrops freeze and hail forms