Transcript what is weather?

WHAT IS WEATHER?
The weather is just the state of the atmosphere at any time, including things such as
temperature, precipitation, air pressure and cloud cover. Daily changes in the weather are
due to winds and storms. Seasonal changes are due to the Earth rotating around the sun.
WHAT CAUSES WEATHER?
Because the Earth is round and not flat, the Sun's rays don't fall evenly on the land and
oceans. The Sun shines more directly near the equator bringing these areas more warmth.
However, the polar regions are at such an angle to the Sun that they get little or no sunlight
during the winter, causing colder temperatures. These differences in temperature create a
restless movement of air and water in great swirling currents to distribute heat energy from
the Sun across the planet. When air in one region is warmer than the surrounding air, it
becomes less dense and begins to rise, drawing more air in underneath. Elsewhere, cooler
denser air sinks, pushing air outward to flow along the surface and complete the cycle.
WHY DO WE HAVE SEASONS?
As the Earth spins on its axis, producing night and day, it also moves about the
Sun in an elliptical (elongated circle) orbit that requires 365 1/4 days to
complete. The Earth's axis is tilted at 23.5 degrees and is why we have seasons.
When the Earth's axis points towards the Sun, it is summer for that hemisphere.
When the Earth's axis points away, winter can be expected.
Water Cycle
What are clouds?
A cloud is a large collection of very tiny droplets of water or ice crystals. The droplets are
so small and light that they can float in the air.
How are clouds formed?
All air contains water, but near the ground it is usually in the form of an invisible gas called
water vapor. When warm air rises, it expands and cools. Cool air can't hold as much water
vapor as warm air, so some of the vapor condenses onto tiny pieces of dust that are
floating in the air and forms a tiny droplet around each dust particle. When billions of
these droplets come together they become a visible cloud.
Why are clouds white?
Since light travels as waves of different lengths, each color has its very own
unique wavelength. Clouds are white because their water droplets or ice
crystals are large enough to scatter the light of the seven wavelengths (red,
orange, yellow, green, blue, indigo, and violet), which combine to produce
white light.
Why do clouds turn gray?
Clouds are made up of tiny water droplets or ice crystals, usually a mixture of
both. The water and ice scatter all light, making clouds appear white. If the
clouds get thick enough or high enough all the light above does not make it
through, hence the gray or dark look. Also, if there are lots of other clouds
around, their shadow can add to the gray or multicolored gray appearance.
Why do clouds float?
A cloud is made up of liquid water droplets. A cloud forms when air is heated
by the sun. As it rises, it slowly cools it reaches the saturation point and
water condenses, forming a cloud. As long as the cloud and the air that its
made of is warmer than the outside air around it, it floats!
How do clouds move?
Clouds move with the wind. High cirrus clouds are pushed along by the jet
stream, sometimes traveling at more than 100 miles-per-hour. When clouds
are part of a thunderstorm they usually travel at 30 to 40 mph.
Why do clouds form at different heights in the atmosphere?
The characteristics of clouds are dictated by the elements available, including
the amount of water vapor, the temperatures at that height, the wind, and
the interplay of other air masses.
How is fog formed?
There are many different types of fog, but fog is mostly formed when
southerly winds bring warm, moist air into a region, possibly ending a cold
outbreak. As the warm, moist air flows over much colder soil or snow, dense
fog often forms. Warm, moist air is cooled from below as it flows over a
colder surface. If the air is near saturation, moisture will condense out of the
cooled air and form fog. With light winds, the fog near the ground can
become thick and reduce visibilities to zero.
WHY IS THE SKY BLUE?
The sun shines white and black light to our planet. The white light has all the
colors in it. In our upper atmosphere, we have dust particles and oxygen
molecules. The white light meaning all of the colors in a rainbow shines
through the upper levels of the atmosphere and the blue light scatters across
the entire planet. That is why our sky is blue. Now, during sunrise and sunset,
the light traveling through atmosphere is longer at the horizon, then if you
were to look up high in the sky. There are more dust particles and oxygen
molecules at the horizon, so that is why you see such pretty colors like red,
oranges and yellows.
Weather Instruments:
http://www.weatherwizkids.com/weatherinstruments.htm
Find answers to your questions:
Weather wizkids –
http://www.weatherwizkids.com
Scroll to the bottom of this page to find
answers to a lot of weather topics.
Here’s another cool site to check out weather:
https://eo.ucar.edu/webweather/