Taking photos in the rain

Picture this. You've planned a day to get out and about to do
some photography but you wake up that morning to a dreary rainy
day.
It's not the weather you typically hope for, but don't
let it dampen your spirits. We've got some great tips to help
you get some stunning shots even when it's miserable outside...
Cover up your camera
There are about a million rain covers for camera gear on the
market. The real problem is having it with you when it starts to
rain. Carry camera rain gear in your bag that won’t take up too
much space.
To keep it cheap, try out a gallon-size plastic bag. In a pinch,
it will do a passable job of keeping a camera dry. Punch a hole in
one end to poke the lens through and stick your hand in the other
end.
Look for porches and awnings
Park under a dry spot and wait for the pictures to come to you.
Just be patient.
Shoot from inside a car
This is often the best course of action, and sometimes it's the
only practical answer. You can often roll down the window and stay
pretty dry, especially if the wind is at your back (coming from the
other side of the car).
Buy an umbrella
Carry a small folding umbrella with you. It would be
helpful to have a trusty assistant (or patient
friend/relative) to carry the umbrella, but if not you can still do
a lot of work just holding the umbrella in the hand that
also grips the camera. A little awkward, but it has the
advantage of keeping the umbrella right over the camera. Remember:
Don't use umbrellas in thunderstorms!
Include the umbrella in your picture
Actually, your own umbrella can work well to compose/frame a
shot. Bring it down into the top of the picture when you are
shooting with a wide angle and it nicely fills the upper part of
the frame, providing a nice visual cue that it is, in fact,
raining. If the streets are full of people under umbrellas, yours
fits in with the crowd. But also if the clouds are bright and the
scene below is dark, use the umbrella to cover up the too-bright
clouds and your scene can suddenly look much better exposed.
Watch for reflections
Unless you are in a downpour, it is difficult to actually see
the rain itself. So you have to leave visual clues that it is
raining. Look for ways that the rain transforms the ordinary into
the extraodinary.
Shoot towards the light
Rain becomes more visible when it is backlit. The light coming
through the raindrops is concentrated and slightly brighter than
the rest of the scene. So find some light sources and shoot toward
it. This could be a streetlight at night, or it could be the sun
breaking though the clouds. Whatever the case, the rules are the
same. One, the more directly you shoot into the light, the better
you can see the raindrops. Two, shoot too directly and the light
source will overpower your exposure. So always seek that magic
angle in between.
Use a little flash
Your flash will light up the raindrops, usually a bad thing
because it will pump out way too much light as it tries to light up
your subject. You don’t want that. But if your camera allows you
to, turn the flash down (to -3.0 stops for example) and it will add
just a little pop to the raindrops. This technique is tricky;
you’ll have to experiment. Maybe it won’t work at all, but if it
does, it can be quite magical. (Also works on snowflakes
sometimes).
Be on the lookout for joy or misery
Rain transforms people. We react to rain with a gamut of
emotions, from rain-drenched commuters to the wondrous joy of
children. Capture those emotions and you’ll have a great rain
picture.
Source: Jim Richardson, National Geographic