The Earth is surrounded by a
thin blanket of air called the
atmosphere.
The atmosphere is a mix of
several different gases like
nitrogen, oxygen, carbon dioxide,
and other.
The atmosphere is made of
several different layers. The
troposphere is the layer closest
to the Earth’s surface.
All of Earth’s life exists in the
troposphere. It is also where all
of Earth’s weather takes place.
Weather is the condition of the
atmosphere at a given time and
place. The four properties of
weather are temperature,
humidity, air pressure, and
precipitation.
Air has weight to it. The force of
air pushing on an area is called
air pressure.
Temperature describes how hot
or cold something is. The sun’s
energy heats the Earth unevenly.
The uneven heating of the Earth’s
surface causes air to move at
different speeds. This moving air
is called wind.
Cool air has higher air pressure
than warmer air. (Cooler air
weighs more than warmer air.)
Air moves from an area of higher
pressure to lower pressure.
Humidity is a measure of how
much moisture (water) is in the
air. This moisture comes from
evaporated water.
Precipitation is any form of water
that falls from clouds. This
included rain, snow, sleet, and
hail.
Meteorologists, weather
scientists, collect data from a
place called a weather station.
They use different kinds of tools
to collect their data.
A hygrometer is a tool that
measures humidity.
A thermometer measures air
temperature in degrees Celsius
(ºC) or degrees Fahrenheit (ºF).
A barometer measures air
pressure.
A rain gauge is a tool that collects
and shows the amount of rainfall.
A wind vane point the direction
from which the wind is blowing.
An anemometer measures wind
speed.
Weather changes day to day,
even hour to hour. But the
pattern of seasonal weather that
happens year after year is
climate.
Things that affect climate are
latitude, global winds, ocean
currents, distance from water,
altitude, and clouds and
precipitation.